arXiv daily: Earth and Planetary Astrophysics (astro-ph.EP)

Authors:Martin Rubin

Abstract: Here we review some of the major findings of the mass spectrometer suite ROSINA on board of ESA's Rosetta spacecraft to comet 67P/Churyumov-Gerasimenko. For more than 2 years, ROSINA continuously measured the composition of the gases sublimating from the comet's nucleus. ROSINA measurements provided insight into the origin of the ices in 67P/Churyumov-Gerasimenko. The obtained molecular, elemental, and isotope abundances revealed a composition more complex than previously known. Furthermore, a subset of these measurements indicate that a substantial fraction of the molecules incorporated into the comet predate the formation of the solar system.

Authors:J. Winkenstern, J. Saur

Abstract: The icy moon Europa is a primary target for the study of ocean worlds. Its subsurface ocean is expected to be subject to asymmetries on global scales (tidal deformation) and local scales (chaos regions, fractures). Here, we investigate the possibility to magnetic sound local asymmetries by calculating the induced magnetic fields generated by a radially symmetric ocean and a small, spherical water reservoir between the ocean and Europa's surface. The consideration of two conductive bodies introduces non-linear magnetic field coupling between them. We construct an analytical model to describe the coupling between two conductive bodies and calculate the induced fields within the parameter space of possible conductivity values and icy crust thicknesses. Given the plasma magnetic field perturbations, we find that a reservoir cannot be detected during a flyby at 25 km altitude using electromagnetic induction. Potential detection of liquid water reservoirs can be achieved by deploying magnetometers on Europa's surface, where one magnetometer is placed directly on the target region of interest and a second one in the nearby vicinity as reference to distinguish from global asymmetries. With this method, the smallest reservoir that can be detected has a radius of 8 km and a conductivity of 30 S/m. Larger reservoirs are resolvable at lower conductivities, with a 20 km reservoir requiring a conductivity of approximately 5 S/m.

Authors:Arnaud Michel, Sarah I. Sadavoy, Patrick D. Sheehan, Leslie W. Looney, Erin G. Cox, John J. Tobin, Nienke van der Marel, Dominique M. Segura-Cox

Abstract: High-resolution, millimeter observations of disks at the protoplanetary stage reveal substructures such as gaps, rings, arcs, spirals, and cavities. While many protoplanetary disks host such substructures, only a few at the younger protostellar stage have shown similar features. We present a detailed search for early disk substructures in ALMA 1.3 and 0.87~mm observations of ten protostellar disks in the Ophiuchus star-forming region. Of this sample, four disks have identified substructure, two appear to be smooth disks, and four are considered ambiguous. The structured disks have wide Gaussian-like rings ($\sigma_R/R_{\mathrm{disk}}\sim0.26$) with low contrasts ($C<0.2$) above a smooth disk profile, in comparison to protoplanetary disks where rings tend to be narrow and have a wide variety of contrasts ($\sigma_R/R_{\mathrm{disk}}\sim0.08$ and $C$ ranges from $0-1$). The four protostellar disks with the identified substructures are among the brightest sources in the Ophiuchus sample, in agreement with trends observed for protoplanetary disks. These observations indicate that substructures in protostellar disks may be common in brighter disks. The presence of substructures at the earliest stages suggests an early start for dust grain growth and, subsequently, planet formation. The evolution of these protostellar substructures is hypothesized in two potential pathways: (1) the rings are the sites of early planet formation, and the later observed protoplanetary disk ring-gap pairs are secondary features, or (2) the rings evolve over the disk lifetime to become those observed at the protoplanetary disk stage.

Authors:J. A. Sturm, M. K. McClure, T. L. Beck, D. Harsono, J. B. Bergner, E. Dartois, A. C. A. Boogert, J. E. Chiar, M. A. Cordiner, M. N. Drozdovskaya, S. Ioppolo, C. J. Law, H. Linnartz, D. C. Lis, G. J. Melnick, B. A. McGuire, J. A. Noble, K. I. Öberg, M. E. Palumbo, Y. J. Pendleton, G. Perotti, K. M. Pontoppidan, D. Qasim, W. R. M. Rocha, H. Terada, R. G. Urso, E. F. van Dishoeck

Abstract: Ices are the main carriers of volatiles in protoplanetary disks and are crucial to our understanding of the chemistry that ultimately sets the organic composition of planets. The ERS program Ice Age on the JWST follows the ice evolution through all stages of star and planet formation. JWST/NIRSpec observations of the edge-on Class II protoplanetary disk HH~48~NE reveal spatially resolved absorption features of the major ice components H$_2$O, CO$_2$, CO, and multiple weaker signatures from less abundant ices NH$_3$, OCN$^-$, and OCS. Isotopologue $^{13}$CO$_2$ ice has been detected for the first time in a protoplanetary disk. Since multiple complex light paths contribute to the observed flux, the ice absorption features are filled in by ice-free scattered light. The $^{12}$CO$_2$/$^{13}$CO$_2$ ratio of 14 implies that the $^{12}$CO$_2$ feature is saturated, without the flux approaching 0, indicative of a very high CO$_2$ column density on the line of sight, and a corresponding abundance with respect to hydrogen that is higher than ISM values by a factor of at least a few. Observations of rare isotopologues are crucial, as we show that the $^{13}$CO$_2$ observation allows us to determine the column density of CO$_2$ to be at an order of magnitude higher than the lower limit directly inferred from the observed optical depth. Radial variations in ice abundance, e.g., snowlines, are significantly modified since all observed photons have passed through the full radial extent of the disk. CO ice is observed at perplexing heights in the disk, extending to the top of the CO-emitting gas layer. We argue that the most likely interpretation is that we observe some CO ice at high temperatures, trapped in less volatile ices like H$_2$O and CO$_2$. Future radiative transfer models will be required to constrain the implications on our current understanding of disk physics and chemistry.

Authors:Evert Nasedkin, Paul Mollière, Doriann Blain

Abstract: petitRADTRANS (pRT) is a fast radiative transfer code used for computing emission and transmission spectra of exoplanet atmospheres, combining a FORTRAN back end with a Python based user interface. It is widely used in the exoplanet community with 161 references in the literature to date, and has been benchmarked against numerous similar tools. The spectra calculated with pRT can be used as a forward model for fitting spectroscopic data using Monte Carlo techniques, commonly referred to as an atmospheric retrieval. The new retrieval module combines fast forward modelling with nested sampling codes, allowing for atmospheric retrievals on a large range of different types of exoplanet data. Thus it is now possible to use pRT to easily and quickly infer the atmospheric properties of exoplanets in both transmission and thermal emission.

Authors:Francesco Flammini Dotti, Roberto Capuzzo-Dolcetta, M. B. N. Kouwenhoven

Abstract: Most stars are born in dense stellar environments where the formation and early evolution of planetary systems may be significantly perturbed by encounters with neighbouring stars. To investigate on the fate of circumstellar gas disks and planets around young stars dense stellar environments, we numerically evolve star-disk-planet systems. We use the $N$-body codes NBODY6++GPU and SnIPES for the dynamical evolution of the stellar population, and the SPH-based code GaSPH for the dynamical evolution of protoplanetary disks. The secular evolution of a planetary system in a cluster differs from that of a field star. Most stellar encounters are tidal, adiabatic and nearly-parabolic. The parameters that characterize the impact of an encounter include the orientation of the protoplanetary disk and planet relative to the orbit of the encountering star, and the orbital phase and the semi-major axis of the planet. We investigate this dependence for close encounters ($r_p/a\leq 100$, where $r_p$ is the periastron distance of the encountering star and $a$ is the semi-major axis of the planet). We also investigate distant perturbers ($r_p/a\gg 100$), which have a moderate effect on the dynamical evolution of the planet and the protoplanetary disk. We find that the evolution of protoplanetary disks in star clusters differs significantly from that of isolated systems. When interpreting the outcome of the planet formation process, it is thus important to consider their birth environments.

Authors:Andrea Bocchieri, Lorenzo V. Mugnai, Enzo Pascale, Quentin Changeat, Giovanna Tinetti

Abstract: The Ariel Space Mission aims to observe a diverse sample of exoplanet atmospheres across a wide wavelength range of 0.5 to 7.8 microns. The observations are organized into four Tiers, with Tier 1 being a reconnaissance survey. This Tier is designed to achieve a sufficient signal-to-noise ratio (S/N) at low spectral resolution in order to identify featureless spectra or detect key molecular species without necessarily constraining their abundances with high confidence. We introduce a P-statistic that uses the abundance posteriors from a spectral retrieval to infer the probability of a molecule's presence in a given planet's atmosphere in Tier 1. We find that this method predicts probabilities that correlate well with the input abundances, indicating considerable predictive power when retrieval models have comparable or higher complexity compared to the data. However, we also demonstrate that the P-statistic loses representativity when the retrieval model has lower complexity, expressed as the inclusion of fewer than the expected molecules. The reliability and predictive power of the P-statistic are assessed on a simulated population of exoplanets with H2-He dominated atmospheres, and forecasting biases are studied and found not to adversely affect the classification of the survey.

Authors:Pedro P. Poblete, Torsten Löhne, Tim D. Pearce, Antranik A. Sefilian

Abstract: Drastic changes in protoplanets' orbits could occur in the early stages of planetary systems through interactions with other planets and their surrounding protoplanetary or debris discs. The resulting planetary system could exhibit orbits with moderate to high eccentricities and/or inclinations, causing planets to perturb one another as well as the disc significantly. The present work studies the evolution of systems composed of an initially inclined planet and a debris disc. We perform N-body simulations of a narrow, self-gravitating debris disc and a single interior Neptune-like planet. We simulate systems with various initial planetary inclinations, from coplanar to polar configurations considering different separations between the planet and the disc. We find that except when the planet is initially on a polar orbit, the planet-disc system tends to reach a quasi-coplanar configuration with low vertical dispersion in the disc. When present, the Zeipel--Kozai--Lidov oscillations induced by the disc pump the planet's eccentricity and, in turn, affect the disc structure. We also find that the resulting disc morphology in most of the simulations looks very similar in both radial and vertical directions once the simulations are converged. This contrasts strongly with massless disc simulations, where vertical disc dispersion is set by the initial disc-planet inclination and can be high for initially highly inclined planets. The results suggest caution in interpreting an unseen planet's dynamical history based only on the disc's appearance.

Authors:David Jewitt, Yonyoung Kim, Jing Li, Max Mutchler

Abstract: The main belt asteroids 458271 (2010 UM26) and 2010 RN221 share almost identical orbital elements and currently appear as comoving objects 30 arcsec apart in the plane of the sky. They are products of the breakup of a parent object, or the splitting of a binary, with a separation age measured in decades rather than thousands or millions of years as for most other asteroid pairs (Vokrouhlicky et al.~2022). The nature of the precursor body and the details of the breakup and separation of the components are unknown. We obtained deep, high resolution imaging using the Hubble Space Telescope to characterize the pair and to search for material in addition to the main components that might have been released upon breakup. The primary and secondary have absolute magnitudes $H$ = 17.98 and 19.69, respectively, and effective diameters 760 m and 350 m (assuming geometric albedo 0.20). The secondary/primary mass ratio is 0.1, assuming equal densities. Time-series photometry shows that the primary rotates with period 5.9 hour and has a small photometric range (0.15 magnitudes), while the period of the secondary is undetermined (but >20 hours) and its lightcurve range is at least 1 magnitude. The primary rotation period and component mass ratio are consistent with a simple model for the breakup of a rotationally unstable precursor. However, unlike other observationally supported instances of asteroid breakup, neither macroscopic fragments nor unresolved material are found remaining in the vicinity of this asteroid pair. We suggest that the pair is a recently dissociated binary, itself formed earlier by rotational instability of 2010 UM26.

Authors:G. Duchene, F. Menard, K. Stapelfeldt, M. Villenave, S. G. Wolff, M. D. Perrin, C. Pinte, R. Tazaki, D. L. Padgett

Abstract: Scattered light imaging of protoplanetary disks provides key insights on the geometry and dust properties in the disk surface. Here we present JWST 2--21\,$\mu$m images of a 1000\,au-radius edge-on protoplanetary disk surrounding an 0.4\,$M_\odot$ young star in Taurus, 2MASS\,J04202144+2813491. These observations represent the longest wavelengths at which a protoplanetary disk is spatially resolved in scattered light. We combine these observations with HST optical images and ALMA continuum and CO mapping. We find that the changes in the scattered light disk morphology are remarkably small across a factor of 30 in wavelength, indicating that dust in the disk surface layers is characterized by an almost gray opacity law. Using radiative transfer models, we conclude that grains up to $\gtrsim10\,\mu$m in size are fully coupled to the gas in this system, whereas grains $\gtrsim100\,\mu$m are strongly settled towards the midplane. Further analyses of these observations, and similar ones of other edge-on disks, will provide strong empirical constraints on disk dynamics and evolution and grain growth models. In addition, the 7.7 and 12.\,$\mu$m JWST images reveal an X-shaped feature located above the warm molecular layer traced by CO line emission. The highest elevations at which this feature is detectable roughly match the maximal extent of the disk in visible wavelength scattered light as well as of an unusual kinematic signature in CO. We propose that these phenomena could be related to a disk wind entraining small dust grains.

Authors:Audrey Chatain, Scot C. R. Rafkin, Alejandro Soto, Enora Moisan, Juan M. Lora, Alice Le Gall, Ricardo Hueso, Aymeric Spiga

Abstract: Titan, the largest moon of Saturn, has many lakes on its surface, formed mainly of liquid methane. Like water lakes on Earth, these methane lakes on Titan likely profoundly affect the local climate. Previous studies (Rafkin and Soto 2020, Chatain et al 2022) showed that Titan's lakes create lake breeze circulations with characteristic dimensions similar to the ones observed on Earth. However, such studies used a model in two dimensions; this work investigates the consequences of the addition of a third dimension to the model. Our results show that 2D simulations tend to overestimate the extension of the lake breeze over the land, and underestimate the strength of the subsidence over the lake, due to divergence/convergence geometrical effects in the mass conservation equations. In addition, 3D simulations including a large scale background wind show the formation of a pocket of accelerated wind behind the lake, which did not form in 2D simulations. An investigation of the effect of shoreline concavity on the resulting air circulation shows the formation of wind currents over peninsulas. Simulations with several lakes can either result in the formation of several individual lake breeze cells (during the day), or the emergence of a large merged cell with internal wind currents between lakes (during the night). Simulations of several real-shaped lakes located at a latitude of 74{\deg}N on Titan at the spring equinox show that larger lakes trigger stronger winds, and that some sections of lakes might accumulate enough methane vapor to form a thin fog. The addition of a third dimension, along with adjustments in the parametrizations of turbulence and subsurface land temperature, results in a reduction in the magnitude of the average lake evaporate rate, namely to ~6 cm/Earth year.

Authors:Olivia Lim, Björn Benneke, René Doyon, Ryan J. MacDonald, Caroline Piaulet, Étienne Artigau, Louis-Philippe Coulombe, Michael Radica, Alexandrine L'Heureux, Loïc Albert, Benjamin V. Rackham, Julien de Wit, Salma Salhi, Pierre-Alexis Roy, Laura Flagg, Marylou Fournier-Tondreau, Jake Taylor, Neil J. Cook, David Lafrenière, Nicolas B. Cowan, Lisa Kaltenegger, Jason F. Rowe, Néstor Espinoza, Lisa Dang, Antoine Darveau-Bernier

Abstract: TRAPPIST-1 is a nearby system of seven Earth-sized, temperate, rocky exoplanets transiting a Jupiter-sized M8.5V star, ideally suited for in-depth atmospheric studies. Each TRAPPIST-1 planet has been observed in transmission both from space and from the ground, confidently rejecting cloud-free, hydrogen-rich atmospheres. Secondary eclipse observations of TRAPPIST-1 b with JWST/MIRI are consistent with little to no atmosphere given the lack of heat redistribution. Here we present the first transmission spectra of TRAPPIST-1 b obtained with JWST/NIRISS over two visits. The two transmission spectra show moderate to strong evidence of contamination from unocculted stellar heterogeneities, which dominates the signal in both visits. The transmission spectrum of the first visit is consistent with unocculted starspots and the second visit exhibits signatures of unocculted faculae. Fitting the stellar contamination and planetary atmosphere either sequentially or simultaneously, we confirm the absence of cloud-free hydrogen-rich atmospheres, but cannot assess the presence of secondary atmospheres. We find that the uncertainties associated with the lack of stellar model fidelity are one order of magnitude above the observation precision of 89 ppm (combining the two visits). Without affecting the conclusion regarding the atmosphere of TRAPPIST-1 b, this highlights an important caveat for future explorations, which calls for additional observations to characterize stellar heterogeneities empirically and/or theoretical works to improve model fidelity for such cool stars. This need is all the more justified as stellar contamination can affect the search for atmospheres around the outer, cooler TRAPPIST-1 planets for which transmission spectroscopy is currently the most efficient technique.

Authors:Leigh N. Fletcher, Oliver R. T. King, Jake Harkett, Heidi B. Hammel, Michael T. Roman, Henrik Melin, Matthew M. Hedman, Julianne I. Moses, Sandrine Guerlet, Stefanie N. Milam, Matthew S. Tiscareno

Abstract: Saturn's northern summertime hemisphere was mapped by JWST/MIRI (4.9-27.9 $\mu$m) in November 2022, tracing the seasonal evolution of temperatures, aerosols, and chemical species in the five years since the end of the Cassini mission. The spectral region between reflected sunlight and thermal emission (5.1-6.8 $\mu$m) is mapped for the first time, enabling retrievals of phosphine, ammonia, and water, alongside a system of two aerosol layers (an upper tropospheric haze $p<0.3$ bars, and a deeper cloud layer at 1-2 bars). Ammonia displays substantial equatorial enrichment, suggesting similar dynamical processes to those found in Jupiter's equatorial zone. Saturn's North Polar Stratospheric Vortex has warmed since 2017, entrained by westward winds at $p<10$ mbar, and exhibits localised enhancements in several hydrocarbons. The strongest latitudinal temperature gradients are co-located with the peaks of the zonal winds, implying wind decay with altitude. Reflectivity contrasts at 5-6 $\mu$m compare favourably with albedo contrasts observed by Hubble, and several discrete vortices are observed. A warm equatorial stratospheric band in 2022 is not consistent with a 15-year repeatability for the equatorial oscillation. A stacked system of windshear zones dominates Saturn's equatorial stratosphere, and implies a westward equatorial jet near 1-5 mbar at this epoch. Lower stratospheric temperatures, and local minima in the distributions of several hydrocarbons, imply low-latitude upwelling and a reversal of Saturn's interhemispheric circulation since equinox. Latitudinal distributions of stratospheric ethylene, benzene, methyl and carbon dioxide are presented for the first time, and we report the first detection of propane bands in the 8-11 $\mu$m region.

Authors:Bhanu Kumar, Rodney L. Anderson, Rafael de la Llave

Abstract: The overlapping of mean-motion resonances is useful for low or zero-propellant space mission design, but while most related prior work uses a planar CRTBP model, tours of multi-moon systems require using resonances affected by two moons. In this work, we investigate Jupiter-Ganymede unstable 4:3 resonant orbits in a concentric circular restricted 4-body model for the Jupiter-Europa-Ganymede system. We show that despite their high order, secondary resonances between these orbits and Europa have a large effect, especially 11/34, 12/37, 23/71, 25/77, 34/105, and 35/108; we also find strong evidence that the associated resonant islands overlap. We then compute many of the new objects which appear inside the secondary resonances, which gives final confirmation of the secondary resonance overlap.

Authors:Ilseung Han, Woojin Kwon, Yusuke Aso, Jaehan Bae, Patrick Sheehan

Abstract: The first step toward planet formation is grain growth from (sub-)micrometer to millimeter/centimeter sizes. Grain growth has been reported not only in Class II protoplanetary disks but also in Class 0/I protostellar envelopes. However, early-stage grain growth occurring in Class 0/I stages has rarely been observed on the protostellar disk scale. Here we present the results from the ALMA Band 3 ($\lambda$ = 3.1 mm) and 7 ($\lambda$ = 0.87 mm) archival data of the Class I protostellar disk WL 17 in the $\rho$ Ophiuchus molecular cloud. Disk substructures are found in both bands, but they are different: while a central hole and a symmetric ring appear in Band 3, an off-center hole and an asymmetric ring are shown in Band 7. Furthermore, we obtain an asymmetric spectral index map with a low mean value of $\alpha$ = 2.28 $\pm$ 0.02, suggestive of grain growth and dust segregation on the protostellar disk scale. Our radiative transfer modeling verifies these two features by demonstrating that 10 cm-sized large grains are symmetrically distributed, whereas 10 $\mu$m-sized small grains are asymmetrically distributed. Also, the analysis shows that the disk is expected to be massive and gravitationally unstable. We thus suggest a single Jupiter-mass protoplanet formed by gravitational instability as the origin of the ring-like structure, grain growth, and dust segregation identified in WL 17.

Authors:G. Chaverot, E. Bolmont, M. Turbet

Abstract: Even if their detection is for now challenging, observation of small terrestrial planets will be easier in a near future thanks to continuous improvements of detection and characterisation instruments. In this quest, climate modeling is a key step to understand their characteristics, atmospheric composition and possible history. If a surface water reservoir is present on such a terrestrial planet, an increase in insolation may lead to a dramatic positive feedback induced by water evaporation: the runaway greenhouse. The resulting rise of global surface temperature leads to the evaporation of the entire water reservoir, separating two very different population of planets: 1) temperate planets with a surface water ocean and 2) hot planets with a puffed atmosphere dominated by water vapor. In this work we use a 3D General Circulation Model (GCM), the Generic-PCM, to study the runaway greenhouse transition, linking temperate and post-runaway states. Our simulations are made of two steps. First, assuming initially a liquid surface ocean, an evaporation phase which enriches the atmosphere in water vapor. Second, when the ocean is considered entirely evaporated, a dry transition phase for which the surface temperature increases dramatically. Finally, it converges on a hot and stable post-runaway state. By describing in detail the evolution of the climate during these two steps, we show a rapid transition of the cloud coverage and of the wind circulation from the troposphere to the stratosphere. By comparing our result to previous studies using 1D models, we discuss the effect of intrinsically 3D processes such as the global dynamics and the clouds, keys to understand the runaway greenhouse. We also explore the potential reversibility of the runaway greenhouse, limited by its radiative unbalance.

Authors:Ryan C. Challener, Emily Rauscher

Abstract: High-precision exoplanet eclipse light curves, like those possible with JWST, enable flux and temperature mapping of exoplanet atmospheres. These eclipse maps will have unprecedented precision, providing an opportunity to constrain current theoretical predictions of exoplanet atmospheres. However, eclipse mapping has unavoidable mathematical limitations because many map patterns are unobservable. This ``null space'' has implications for making comparisons between predictions from general circulation models (GCMs) and the observed planet maps, and, thus, affects our understanding of the physical processes driving the observed maps. We describe the eclipse-mapping null space and show how GCM forward models can be transformed to their observable modes for more appropriate comparison with retrieved eclipse maps, demonstrated with applications to synthetic data of an ultra-hot Jupiter and a cloudy warm Jupiter under JWST-best-case- and extreme-precision observing scenarios. We show that the effects of the null space can be mitigated and manipulated through observational design, and JWST exposure times are short enough to not increase the size of the null space. Furthermore, we show the mathematical connection between the null space and the ``eigenmapping'' method, demonstrating how eigenmaps can be used to understand the null space in a model-independent way. We leverage this connection to incorporate null-space uncertainties in retrieved maps, which increases the uncertainties to now encompass the ground truth for synthetic data. The comparisons between observed maps and forward models that are enabled by this work, and the improved eclipse-mapping uncertainties, will be critical to our interpretation of multidimensional aspects of exoplanets in the JWST era.

Authors:Christopher R. Glein, William M. Grundy, Jonathan I. Lunine, Ian Wong, Silvia Protopapa, Noemi Pinilla-Alonso, John A. Stansberry, Bryan J. Holler, Jason C. Cook, Ana Carolina Souza-Feliciano

Abstract: Dwarf planets Eris and Makemake have surfaces bearing methane ice of unknown origin. D/H ratios were recently determined from James Webb Space Telescope (JWST) observations of Eris and Makemake (Grundy et al., submitted), giving us new clues to decipher the origin of methane. Here, we develop geochemical models to test if the origin of methane could be primordial, derived from CO$_2$ or CO ("abiotic"), or sourced by organics ("thermogenic"). We find that primordial methane is inconsistent with the observational data, whereas both abiotic and thermogenic methane can have D/H ratios that overlap the observed ranges. This suggests that Eris and Makemake either never acquired a significant amount of methane during their formation, or their original inventories were removed and then replaced by a source of internally produced methane. Because producing abiotic or thermogenic methane likely requires temperatures in excess of ~150{\deg}C, we infer that Eris and Makemake have rocky cores that underwent substantial radiogenic heating. Their cores may still be warm/hot enough to produce methane. This heating could have driven hydrothermal circulation at the bottom of an ice-covered ocean to generate abiotic methane, and/or metamorphic reactions involving accreted organic matter could have occurred in response to heating in the deeper interior, generating thermogenic methane. Additional analyses of thermal evolution model results and predictions from modeling of D-H exchange in the solar nebula support our findings of elevated subsurface temperatures and a lack of primordial methane on Eris and Makemake. It remains an open question whether their D/H ratios may have evolved subsequent to methane outgassing. Recommendations are given for future activities to further test proposed scenarios of abiotic and thermogenic methane production on Eris and Makemake, and to explore these worlds up close.

Authors:Nikku Madhusudhan, Subhajit Sarkar, Savvas Constantinou, Måns Holmberg, Anjali Piette, Julianne I. Moses

Abstract: The search for habitable environments and biomarkers in exoplanetary atmospheres is the holy grail of exoplanet science. The detection of atmospheric signatures of habitable Earth-like exoplanets is challenging due to their small planet-star size contrast and thin atmospheres with high mean molecular weight. Recently, a new class of habitable exoplanets, called Hycean worlds, has been proposed, defined as temperate ocean-covered worlds with H2-rich atmospheres. Their large sizes and extended atmospheres, compared to rocky planets of the same mass, make Hycean worlds significantly more accessible to atmospheric spectroscopy with the JWST. Here we report a transmission spectrum of the candidate Hycean world, K2-18 b, observed with the JWST NIRISS and NIRSpec instruments in the 0.9-5.2 $\mu$m range. The spectrum reveals strong detections of methane (CH4) and carbon dioxide (CO2) at 5$\sigma$ and 3$\sigma$ confidence, respectively, with high volume mixing ratios of ~1% each in a H2-rich atmosphere. The abundant CH4 and CO2 along with the non-detection of ammonia (NH3) are consistent with chemical predictions for an ocean under a temperate H2-rich atmosphere on K2-18 b. The spectrum also suggests potential signs of dimethyl sulfide (DMS), which has been predicted to be an observable biomarker in Hycean worlds, motivating considerations of possible biological activity on the planet. The detection of CH4 resolves the long-standing missing methane problem for temperate exoplanets and the degeneracy in the atmospheric composition of K2-18 b from previous observations. We discuss possible implications of the findings, open questions, and future observations to explore this new regime in the search for life elsewhere.

Authors:Nataliea Lowson, George Zhou, Chelsea X. Huang, Duncan J. Wright, Billy Edwards, Emma Nabbie, Alex Venner, Samuel N. Quinn, Karen A. Collins, Edward Gillen, Matthew Battley, Amaury Triaud, Coel Hellier, Sara Seager, Joshua N. Winn, Jon M. Jenkins, Bill Wohler, Avi Shporer, Richard P. Schwarz, Felipe Murgas, Enric Pallé, David R. Anderson, Richard G. West, Robert A. Wittenmyer, Brendan P. Bowler, Jonathan Horner, Stephen R. Kane, John Kielkopf, Peter Plavchan, Hui Zhang, Tyler Fairnington, Jack Okumura, Matthew W. Mengel, Brett C. Addison

Abstract: We report the discovery of two mini-Neptunes in near 2:1 resonance orbits ($P=7.610303$ d for HIP 113103 b and $P=14.245651$ d for HIP 113103 c) around the adolescent K-star HIP 113103 (TIC 121490076). The planet system was first identified from the TESS mission, and was confirmed via additional photometric and spectroscopic observations, including a $\sim$17.5 hour observation for the transits of both planets using ESA CHEOPS. We place $\leq4.5$ min and $\leq2.5$ min limits on the absence of transit timing variations over the three year photometric baseline, allowing further constraints on the orbital eccentricities of the system beyond that available from the photometric transit duration alone. With a planetary radius of $R_{p}=1.829^{+0.096}_{-0.067}\,R_{\oplus}$, HIP 113103 b resides within the radius gap, and this might provide invaluable information on the formation disparities between super-Earths and mini-Neptunes. Given the larger radius $R_{p}=2.40^{+0.10}_{-0.08}\,R_{\oplus}$ for HIP 113103 c, and close proximity of both planets to HIP 113103, it is likely that HIP 113103 b might have lost (or is still losing) its primordial atmosphere. We therefore present simulated atmospheric transmission spectra of both planets using JWST, HST, and Twinkle. It demonstrates a potential metallicity difference (due to differences in their evolution) would be a challenge to detect if the atmospheres are in chemical equilibrium. As one of the brightest multi sub-Neptune planet systems suitable for atmosphere follow up, HIP 113103 b and HIP 113103 c could provide insight on planetary evolution for the sub-Neptune K-star population.

Authors:Alan J. Alves-Carmo, Timothée Vaillant, Alexandre C. M. Correia

Abstract: The complex classification of trans-Neptunian objects (TNOs) that are captured in mean-motion resonances (MMRs) and the constraint of their multiple origins are two significant open problems concerning the Solar System. The case-by-case study of the different MMRs and their characteristics provide information about their origin and dynamics, which helps us to understand the early stages of the Solar System evolution. In this paper, we study the dynamics of the detected TNOs close to a 3/1 MMR with Neptune. We initially use a semi-analytic three-body model to investigate the coplanar secular dynamics of these objects and find the stationary points. We then use surface sections and stability maps to analyse the non-averaged dynamics. These methods allow us to isolate the different stability regions and determine the extent of the chaotic regions. We show that stability maps are an extremely powerful tool for studying the resonant dynamics when they are computed in terms of the resonant angle. We then use these maps to study the non-planar three-body problem and the full dynamics in the presence of planetary perturbations. We confirm that TNOs near the 3/1 MMR regions can exist at very high inclinations. In the framework of the three-body problem, many of these objects can also be stable outside the 3/1 MMR owing to a Kozai secular resonance. However, when we take into account the perturbations of the four giant planets, the Kozai regions disappear and only the 3/1 MMR region remains, with eccentricities $e \lesssim 0.5$.

Authors:Alexander de Becker University of Liège University of Hong Kong, Linus Head University of Liège, Bertrand Bonfond University of Liège, Emmanuël Jehin University of Liège, Jean Manfroid University of Liège, Zhonghua Yao Chinese Academy of Sciences, Binzheng Zhang University of Hong Kong, Denis Grodent University of Liège, Nicholas Schneider University of Colorado, Zouhair Benkhaldoun Oukaimeden Observatory

Abstract: Io is the most volcanically active body in the Solar System. This volcanic activity results in the ejection of material into Io's atmosphere, which may then escape from the atmosphere to form various structures in the jovian magnetosphere, including the plasma torus and clouds of neutral particles. The physical processes involved in the escape of particles - for example, how the volcanoes of Io provide material to the plasma torus - are not yet fully understood. In particular, it is not clear to what extent the sodium jet, one of the sodium neutral clouds related to Io, is a proxy of processes that populate the various reservoirs of plasma in Jupiter's magnetosphere. Here, we report on observations carried out over 17 nights in 2014-2015, 30 nights in 2021, and 23 nights in 2022-2023 with the TRAPPIST telescopes, in which particular attention was paid to the sodium jet and the quantification of their physical properties (length, brightness). It was found that these properties can vary greatly from one jet to another and independently of the position of Io in its orbit. No clear link was found between the presence of jets and global brightening of the plasma torus and extended sodium nebula, indicating that jets do not contribute straightforwardly to their population. This work also demonstrates the advantage of regular and long-term monitoring to understanding the variability of the sodium jet and presents a large corpus of jet detections against which work in related fields may compare.

Authors:Marie Yseboodt, Rose-Marie Baland, Sébastien Le Maistre

Abstract: The rotation and orientation of Mars is commonly described using two different sets of angles, namely the Euler angles wrt the Mars orbit plane and the right ascension, declination, and prime meridian location angles wrt the Earth equator at J2000 (as adopted by the IAU). We propose a formulation for both these sets of angles, which consists of the sum of a second degree polynomial and of periodic and Poisson series. Such a formulation is shown here to enable accurate (and physically sound) transformation from one set of angles to the other. The transformation formulas are provided and discussed in this paper. In particular, we point that the quadratic and Poisson terms are key ingredients to reach a transformation precision of 0.1 mas, even 30 years away from the reference epoch of the rotation model (e.g. J2000). Such a precision is required to accurately determine the smaller and smaller geophysical signals observed in the high-accuracy data acquired from the surface of Mars. In addition, we present good practices to build an accurate Martian rotation model over a long time span (30 years around J2000) or over a shorter one (e.g. lifetime of a space mission). We recommend to consider the J2000 mean orbit of Mars as the reference plane for Euler angles. An accurate rotation model should make use of up-to-date models for the rigid and liquid nutations, relativistic corrections in rotation, and polar motion induced by the external torque. Our transformation model and recommendations can be used to define the future IAU solution for the rotation and orientation of Mars using right ascension, declination, and prime meridian location. In particular, thanks to its quadratic terms, our transformation model does not introduce arbitrary and non-physical terms of very long period and large amplitudes, thus providing unbiased values of the rates and epoch values of the angles.

Authors:Daniel Kitzmann, Joachim W. Stock, A. Beate C. Patzer

Abstract: Cool astrophysical objects, such as (exo)planets, brown dwarfs, or asymptotic giant branch stars, can be strongly affected by condensation. Condensation does not only directly affect the chemical composition of the gas phase by removing elements but the condensed material also influences other chemical and physical processes in these object. This includes, for example, the formation of clouds in planetary atmospheres and brown dwarfs or the dust-driven winds of evolved stars. In this study we introduce FastChem Cond, a new version of the FastChem equilibrium chemistry code that adds a treatment of equilibrium condensation. Determining the equilibrium composition under the impact of condensation is complicated by the fact that the number of condensates that can exist in equilibrium with the gas phase is limited by a phase rule. However, this phase rule does not directly provide information on which condensates are stable. As a major advantage of FastChem Cond is able to automatically select the set stable condensates satisfying the phase rule. Besides the normal equilibrium condensation, FastChem Cond can also be used with the rainout approximation that is commonly employed in atmospheres of brown dwarfs or (exo)planets. FastChem Cond is available as open-source code, released under the GPLv3 licence. In addition to the C++ code, FastChem Cond also offers a Python interface. Together with the code update we also add about 290 liquid and solid condensate species to FastChem.

Authors:Ogutu B. Osoro, Edward J. Oughton, Andrew R. Wilson, Akhil Rao

Abstract: The growth of mega-constellations is rapidly increasing the number of rocket launches required to place new satellites in space. While Low Earth Orbit (LEO) broadband satellites help to connect unconnected communities and achieve the Sustainable Development Goals, there are also a range of negative environmental externalities, from the burning of rocket fuels and resulting environmental emissions. We present sustainability analytics for phase 1 of the three main LEO constellations including Amazon Kuiper (3,236 satellites), OneWeb (648 satellites), and SpaceX Starlink (4,425 satellites). In baseline scenarios over five years, we find a per subscriber carbon dioxide equivalent (CO$_2$eq) of 0.70$\pm$0.34 tonnes for Kuiper, 1.41$\pm$0.71 tonnes for OneWeb and 0.47$\pm$0.15 tonnes CO$_2$eq/subscriber for Starlink. However, in the worst-case emissions scenario these values increase to 3.02$\pm$1.48 tonnes for Kuiper, 1.7$\pm$0.71 tonnes for OneWeb and 1.04$\pm$0.33 tonnes CO$_2$eq/subscriber for Starlink, more than 31-91 times higher than equivalent terrestrial mobile broadband. Importantly, phase 2 constellations propose to increase the number of satellites by an order-of-magnitude higher, highlighting the pressing need to mitigate negative environmental impacts. Strategic choices in rocket design and fuel options can help to substantially mitigate negative sustainability impacts.

Authors:Matija Ćuk, Douglas P. Hamilton, David A. Minton, Sarah T. Stewart

Abstract: We identify a new mechanism that can lead to the destruction of small, close-in planetary satellites. If a small moon close to the planet has a sizable eccentricity and inclination, its ejecta that escape to planetocentric orbit would often re-impact with much higher velocity due to the satellite's and the fragment's orbits precessing out of alignment. If the impacts of returning ejecta result in net erosion, a runaway process can occur which may end in disruption of the satellite, and we term this process ``sesquinary catastrophe''. We expect the moon to re-accrete, but on an orbit with significantly lower eccentricity and inclination. We find that the large majority of small close-in moons in the Solar System, have orbits that are immune to sesquinary catastrophe. The exceptions include a number of resonant moonlets of Saturn for which resonances may affect the velocities of re-impact of their own debris. Additionally, we find that Neptune's moon Naiad (and to a lesser degree, Jupiter's Thebe) must have substantial internal strength, in line with prior estimates based on Roche limit stability. We also find that sesquinary instability puts important constraints on the plausible past orbits of Phobos and Deimos or their progenitors.

Authors:Sanchit Kumar, Sumit Kumar, Sharma S. R. K. C. Yamijala

Abstract: "Hot atoms", which are atoms in their excited states, transfer their energy to the surrounding atmosphere through collisions. This process of energy transfer is known as thermalization, and it plays a crucial role in various astrophysical and atmospheric processes. Thermalization of hot atoms is mainly governed by the amount of species present in the surrounding atmosphere and the collision cross-section between the hot atoms and surrounding species. In this work, we investigated the elastic and inelastic collisions between hot oxygen atoms and neutral N$_2$ molecules, relevant to oxygen gas escape from the martian atmosphere and for characterizing the chemical reactions in hypersonic flows. We conducted a series of quantum scattering calculations between various isotopes of O($^3P$) atoms and N$_2$ molecules across a range of collision energies (0.3 to 4 eV), and computed both their differential and collision cross-sections using quantum time$-$independent coupled-channel approach. Our differential cross-section results indicate a strong preference for forward scattering over sideways or backward scattering, and this anisotropy in scattering is further pronounced at higher collision energies. By comparing the cross-sections of three oxygen isotopes, we find that the heavier isotopes consistently have larger collision cross-sections than the lighter isotopes over the entire collision energy range examined. However, for all the isotopes, the variation of collision cross-section with respect to collision energy is the same. As a whole, the present study contributes to a better understanding of the energy distribution and thermalization processes of hot atoms within atmospheric environments. Specifically, the cross$-$sectional data presented in this work is directly useful in improving the accuracy of energy relaxation modeling of O and N$_2$ collisions over Mars and Venus atmospheres.

Authors:Andrea C. Morelli, Alessandra Mannocchi, Carmine Giordano, Fabio Ferrari, Francesco Topputo

Abstract: (99942) Apophis is a potentially hazardous asteroid that will closely approach the Earth on April 13, 2029. Although the likelihood of an impact has been ruled out, this close encounter represents a unique opportunity for planetary science and defense. By investigating the physical and dynamical changes induced by this interaction, valuable insights into asteroid cohesion, strength, and internal structure can be obtained. In light of these circumstances, a fast mission to Apophis holds great scientific importance and potential for understanding potentially hazardous asteroids. To this aim, ESA proposed the mission RAMSES (Rapid Apophis Mission for SEcurity and Safety) to reach Apophis before its close encounter. In this context, the paper focuses on the reachability analysis of (99942) Apophis, examining thousands of trajectories departing from Earth and reaching the asteroid before the fly-by, using a low-thrust spacecraft. A two-layer approach combining direct sequential convex programming and an indirect method is employed for fast and reliable trajectory optimization. The results reveal multiple feasible launch windows and provide essential information for mission planning and system design.

Authors:Rajeeb Sharma Insa Choi, Jes K. Jørgensen Insa Choi, Sacha Gavino Insa Choi, Nagayoshi Ohashi Insa Choi, John J. Tobin Insa Choi, Zhe-Yu Daniel Lin Insa Choi, Zhi-Yun Li Insa Choi, Shigehisa Takakuwa Insa Choi, Chang Won Lee Insa Choi, Jinshi Sai Insa Choi, Woojin Kwon, Itziar de Gregorio-Monsalvo, Alejandro Santamaría-Miranda, Hsi-Wei Yen, Yuri Aikawa, Yusuke Aso, Shih-Ping Lai, Jeong-Eun Lee, Leslie W. Looney, Nguyen Thi Phuong, Travis J. Thieme, Jonathan P. Williams

Abstract: We present high-resolution, high-sensitivity observations of the Class 0 protostar RCrA IRS5N as part of the Atacama Large Milimeter/submilimeter Array (ALMA) large program Early Planet Formation in Embedded Disks (eDisk). The 1.3 mm continuum emission reveals a flattened continuum structure around IRS5N, consistent with a protostellar disk in the early phases of evolution. The continuum emission appears smooth and shows no substructures. However, a brightness asymmetry is observed along the minor axis of the disk, suggesting the disk is optically and geometrically thick. We estimate the disk mass to be between 0.007 and 0.02 M$_{\odot}$. Furthermore, molecular emission has been detected from various species, including C$^{18}$O (2$-$1), $^{12}$CO (2$-$1), $^{13}$CO (2$-$1), and H$_2$CO (3$_{0,3}-2_{0,2}$, 3$_{2,1}-2_{2,0}$, and 3$_{2,2}-2_{2,1}$). By conducting a position-velocity analysis of the C$^{18}$O (2$-$1) emission, we find that the disk of IRS5N exhibits characteristics consistent with Keplerian rotation around a central protostar with a mass of approximately 0.3 M$_{\odot}$. Additionally, we observe dust continuum emission from the nearby binary source, IRS5a/b. The emission in $^{12}$CO toward IRS5a/b seems to emanate from IRS5b and flow into IRS5a, suggesting material transport between their mutual orbits. The lack of a detected outflow and large-scale negatives in \tlvco~observed toward IRS5N suggests that much of the flux from IRS5N is being resolved out. Due to this substantial surrounding envelope, the central IRS5N protostar is expected to be significantly more massive in the future.

Authors:S. I. Ipatov

Abstract: Estimates of the size of the feeding zone of the planet Proxima Centauri c have been made at initial orbital eccentricities of planetesimals equal to 0.02 or 0.15. The research is based on the results of modeling of the evolution of planetesimals' orbits under the influence of the star and planets Proxima Centauri c and b. The considered time interval reached a billion years. It was found that after the accumulation of the planet Proxima Centauri c some planetesimals may have continues to move in stable elliptical orbits within its feeding zone, largely cleared of planetesimals. Usually such planetesimals can move in some resonances with the planet (Proxima Centauri c), for example, in the resonance 1:1 (as Jupiter Trojans), 5:4 and 3:4 and usually have small eccentricities. Some planetesimals that moved for a long time (1-2 million years) along chaotic orbits fell into the resonances 5:2 and 3:10 with the planet Proxima Centauri c and moved in them at least tens of millions of years.

Authors:Bertram Bitsch, Jingyi Mah

Abstract: Giant exoplanets seem to have on average a much larger heavy element content than the solar system giants. Past attempts to explain these heavy element contents include collisions between planets, accretion of volatile rich gas and accretion of gas enriched in micro-metre sized solids. However, these different theories individually could not explain the heavy element content of giants and the volatile to refractory ratios in atmospheres of giant planets at the same time. Here we combine the approaches of gas accretion enhanced with vapor and small micro-meter sized dust grains. As pebbles drift inwards, the volatile component evaporates and enriches the disc, while the smaller silicate core of the pebble continues to move inwards. The smaller silicate pebbles drift slower, leading to a pile-up of material interior to the water ice line, increasing the dust-to-gas ratio interior to the ice line. Under the assumption that these small dust grains follow the motion of the gas, gas accreting giants accrete large fractions of small solids in addition to the volatile vapor. The effectiveness of the solid enrichment requires a large disc radius to maintain the pebble flux for a long time and a large viscosity that reduces the size and inward drift of the small dust grains. However, this process depends crucially on the debated size difference of the pebbles interior and exterior of the water ice line. On the other hand, the volatile component released by the inward drifting pebbles can lead to a large enrichment with heavy element vapor, independently of a size difference of pebbles interior and exterior to the water ice line. Our model stresses the importance of the disc's radius and viscosity on the enrichment of dust and vapor. Consequently we show how our model could explain the heavy element content of the majority of giant planets by using combined estimates of dust and vapor enrichment.

Authors:Robin Baeyens, Jean-Michel Désert, Annemieke Petrignani, Ludmila Carone, Aaron David Schneider

Abstract: Recent observations have resulted in the detection of chemical gradients on ultra-hot gas giants. Notwithstanding their high temperature, chemical reactions in ultra-hot atmospheres may occur in disequilibrium, due to vigorous day-night circulation and intense UV radiation from their stellar hosts. The goal of this work is to explore whether photochemistry is affecting the composition of ultra-hot giant planets, and if it can introduce horizontal chemical gradients. In particular, we focus on hydrogen cyanide (HCN) on WASP-76 b, as it is a photochemically active molecule with a reported detection on only one side of this planet. We use a pseudo-2D chemical kinetics code to model the chemical composition of WASP-76 b along its equator. Our approach improves on chemical equilibrium models by computing vertical mixing, horizontal advection, and photochemistry. We find that production of HCN is initiated through thermal and photochemical dissociation of CO and N2 on the day side of WASP-76 b, which are subsequently transported to the night side via the equatorial jet stream. This process results in an HCN gradient with a maximal abundance on the planet's morning limb. We verified that photochemical dissociation is a necessary condition for this mechanism, as thermal dissociation alone proves insufficient. Other species produced via night-side disequilibrium chemistry are SO2 and S2. Our model acts as a proof of concept for chemical gradients on ultra-hot exoplanets. We demonstrate that even ultra-hot planets can exhibit disequilibrium chemistry and recommend that future studies do not neglect photochemistry in their analyses of ultra-hot planets.

Authors:Kiyoaki Doi, Akimasa Kataoka

Abstract: The dust size in protoplanetary disks is a crucial parameter for understanding planet formation, while the observational constraints on dust size distribution have large uncertainties. In this study, we present a new method to constrain the dust size distribution from the dust spatial distribution, utilizing the fact that larger dust grains are more spatially localized. We analyze the ALMA Band 6 (1.25 mm) and Band 4 (2.14 mm) high-resolution images and constrain the dust size distribution in the two rings of the HD 163296 disk. We find that the outer ring at 100 au appears narrower at the longer wavelengths, while the inner ring at 67 au appears to have similar widths across the two wavelengths. We model dust rings trapped at gas pressure maxima, where the dust grains follow a power-law size distribution, and the dust grains of a specific size follow a Gaussian spatial distribution with the width depending on the grain size. By comparing the observations with the models, we constrain the maximum dust size $a_{\mathrm{max}}$ and the exponent of the dust size distribution $p$. We constrain that $0.9 \ \mathrm{mm} < a_{\mathrm{max}} < 5 \ \mathrm{mm}$ and $p < 3.3$ in the inner ring, and $a_{\mathrm{max}} > 3 \times 10^1 \ \mathrm{mm}$ and $3.4 < p < 3.7$ in the outer ring. The larger maximum dust size in the outer ring implies a spatial dependency in dust growth, potentially influencing the formation location of the planetesimals. We further discuss the turbulence strength $\alpha$ derived from the constrained dust spatial distribution, assuming equilibrium between turbulent diffusion and accumulation of dust grains.

Authors:Sheng Yang, Liangyu Wu, Zekai Zheng, Masahiro Ogihara, Kangrou Guo, Wenzhan Ouyang, Yaxing He

Abstract: Studying the orbital stability of multi-planet systems is essential to understand planet formation, estimate the stable time of an observed planetary system, and advance population synthesis models. Although previous studies have primarily focused on ideal systems characterized by uniform orbital separations, in reality a diverse range of orbital separations exists among planets within the same system. This study focuses on investigating the dynamical stability of systems with non-uniform separation. We considered a system with 10 planets with masses of $10^{-7}$ solar masses around a central star with a mass of $1$ solar mass. We performed more than 100,000 runs of N-body simulations with different parameters. Results demonstrate that reducing merely one pair of planetary spacing leads to an order of magnitude shorter orbital crossing times that could be formulated based on the Keplerian periods of the closest separation pair. Furthermore, the first collisions are found to be closely associated with the first encounter pair that is likely to be the closest separation pair initially. We conclude that when estimating the orbital crossing time and colliding pairs in a realistic situation, updating the formula derived for evenly spaced systems would be necessary.

Authors:S. A. Stern, O. L. White, Wm. Grundy, B. A. Keeney, J. D. Hofgartner, D. Nesvorny, W. B. McKinnon, D. C. Richardson, J. C. Marohnic, A. J. Verbiscer, S. D. Benecchi, P. M. Schenk, J. M. Moore

Abstract: We report on a study of the mounds that dominate the appearance of Kuiper Belt Object (KBO) (486958) Arrokoth's larger lobe, named Wenu. We compare the geological context of these mounds, measure and intercompare their shapes, sizes/orientations, reflectance, and colors. We find the mounds are broadly self-similar in many respects and interpret them as the original building blocks of Arrokoth. It remains unclear why these building blocks are so similar in size, and this represents a new constrain and challenge for solar system formation models. We then discuss the interpretation of this interpretation.

Authors:Fleur Seuren, Santiago A. Triana, Jérémy Rekier, Ankit Barik, Tim Van Hoolst

Abstract: Observational constraints on Mercury's thermal evolution and magnetic field indicate that the top part of the fluid core is stably stratified. Here we compute how a stable layer affects the core flow in response to Mercury's main 88-day longitudinal libration, assuming various degrees of stratification, and study whether the core flow can modify the libration amplitude through viscous and electromagnetic torques acting on the core-mantle boundary (CMB). We show that the core flow strongly depends on the strength of the stratification near the CMB but that the influence of core motions on libration is negligible with or without a stably stratified layer. A stably stratified layer at the top of the core can however prevent resonant behaviour with gravito-inertial modes by impeding radial motions and promote a strong horizontal flow near the CMB. The librationally driven flow is likely turbulent and might produce a non-axisymmetric induced magnetic field with a strength of the order of 1$\%$ of Mercury's dipolar field.

Authors:Paolo Simonetti, Giovanni Vladilo, Stavro L. Ivanovski, Laura Silva, Lorenzo Biasiotti, Michele Maris, Giuseppe Murante, Erica Bisesi, Sergio Monai

Abstract: Despite decades of scientific research on the subject, the climate of the first 1.5 Gyr of Mars history has not been fully understood yet. Especially challenging is the need to reconcile the presence of liquid water for extended periods of time on the martian surface with the comparatively low insolation received by the planet, a problem which is known as the Faint Young Sun (FYS) Paradox. In this paper we use ESTM, a latitudinal energy balance model with enhanced prescriptions for meridional heat diffusion, and the radiative transfer code EOS to investigate how seasonal variations of temperature can give rise to local conditions which are conductive to liquid water runoffs. We include the effects of the martian dichotomy, a northern ocean with either 150 or 550 m of Global Equivalent Layer (GEL) and simplified CO$_2$ or H$_2$O clouds. We find that 1.3-to-2.0 bar CO$_2$-dominated atmospheres can produce seasonal thaws due to inefficient heat redistribution, provided that the eccentricity and the obliquity of the planet are sufficiently different from zero. We also studied the impact of different values for the argument of perihelion. When local favorable conditions exist, they nearly always persist for $>15\%$ of the martian year. These results are obtained without the need for additional greenhouse gases (e.g. H$_2$, CH$_4$) or transient heat-injecting phenomena (e.g. asteroid impacts, volcanic eruptions). Moderate amounts (0.1 to 1\%) of CH$_4$ significantly widens the parameter space region in which seasonal thaws are possible.

Authors:Xi Zhang

Abstract: We propose a general principle that under the radiative-convective equilibrium, the spatial and temporal variations in a planet's surface and atmosphere tend to increase its cooling. This principle is based on Jensen's inequality and the curvature of the response functions of surface temperature and outgoing cooling flux to changes in incoming stellar flux and atmospheric opacity. We use an analytical model to demonstrate that this principle holds for various planet types: (1) on an airless planet, the mean surface temperature is lower than its equilibrium temperature; (2) on terrestrial planets with atmospheres, the inhomogeneity of incoming stellar flux and atmospheric opacity reduces the mean surface temperature; (3) on giant planets, inhomogeneously distributed stellar flux and atmospheric opacity increase the outgoing infrared flux, cooling the interior. Although the inhomogeneity of visible opacity might sometimes heat the atmosphere, the effect is generally much smaller than the inhomogeneous cooling effect of infrared opacity. Compared with the homogeneous case, the mean surface temperature on inhomogeneous terrestrial planets can decrease by more than 20\%, and the internal heat flux on giant planets can increase by over an order of magnitude. Despite simplifications in our analytical framework, the effect of stellar flux inhomogeneity appears to be robust, while further research is needed to fully understand the effects of opacity inhomogeneity in more realistic situations. This principle impacts our understanding of planetary habitability and the evolution of giant planets using low-resolution and one-dimensional frameworks that may have previously overlooked the role of inhomogeneity.

Authors:Xi Zhang

Abstract: We generalize the theory of the inhomogeneity effect to enable comparison among different inhomogeneous planets. A metric of inhomogeneity based on the cumulative distribution function is applied to investigate the dependence of planetary cooling on previously overlooked parameters. The mean surface temperature of airless planets increases with rotational rate and surface thermal inertia, which bounds the value in the tidally locked configuration and the equilibrium temperature. Using an analytical model, we demonstrate that the internal heat flux of giant planets exhibits significant spatial variability, primarily emitted from the nightside and high-latitude regions acting as ``radiator fins." Given a horizontally uniform interior temperature in the convective zone, the outgoing internal flux increases up to several folds as the inhomogeneity of the incoming stellar flux increases. The enhancement decreases with increasing heat redistribution through planetary dynamics or rotation. The outgoing internal flux on rapidly rotating planets generally increases with planetary obliquity and orbital eccentricity. The radiative timescale and true anomaly of the vernal equinox also play significant roles. If the radiative timescale is long, the outgoing internal flux shows a slightly decreasing but nonlinear trend with obliquity. Our findings indicate that rotational and orbital states greatly influence the cooling of planets and impact the interior evolution of giant planets, particularly for tidally locked planets and planets with high eccentricity and obliquity (such as Uranus), as well as the spatial and temporal variations of their cooling fluxes.

Authors:Xi Zhang, Cheng Li, Huazhi Ge, Tianhao Le

Abstract: The interior flux of a giant planet impacts atmospheric motion, and the atmosphere dictates the interior's cooling. Here we use a non-hydrostatic general circulation model (SNAP) coupled with a multi-stream multi-scattering radiative module (HARP) to simulate the weather impacts on the heat flow of hot Jupiters. We found that the vertical heat flux is primarily transported by convection in the lower atmosphere and regulated by dynamics and radiation in the overlying ``radiation-circulation" zone. The temperature inversion occurs on the dayside and reduces the upward radiative flux. The atmospheric dynamics relay the vertical heat transport until the radiation becomes efficient in the upper atmosphere. The cooling flux increases with atmospheric drag due to increased day-night contrast and spatial inhomogeneity. The temperature dependence of the infrared opacity greatly amplifies the opacity inhomogeneity. Although atmospheric circulation could transport heat downward in a narrow region above the radiative-convective boundary, the opacity inhomogeneity effect overcomes the dynamical effect and leads to a larger overall interior cooling than the local simulations with the same interior entropy and stellar flux. The enhancement depends critically on the equilibrium temperature, drag, and atmospheric opacity. In a strong-drag atmosphere hotter than 1600 K, a significant inhomogeneity effect in three-dimensional (3D) models can boost interior cooling several-fold compared to the 1D radiative-convection equilibrium models. This study confirms the analytical argument of the inhomogeneity effect in Zhang (2023ab). It highlights the importance of using 3D atmospheric models in understanding the inflation mechanisms of hot Jupiters and giant planet evolution in general.

Authors:Martin Turbet, Thomas J. Fauchez, Jeremy Leconte, Emeline Bolmont, Guillaume Chaverot, Francois Forget, Ehouarn Millour, Franck Selsis, Benjamin Charnay, Elsa Ducrot, Michaël Gillon, Alice Maurel, Geronimo L. Villanueva

Abstract: Understanding the set of conditions that allow rocky planets to have liquid water on their surface -- in the form of lakes, seas or oceans -- is a major scientific step to determine the fraction of planets potentially suitable for the emergence and development of life as we know it on Earth. This effort is also necessary to define and refine the so-called "Habitable Zone" (HZ) in order to guide the search for exoplanets likely to harbor remotely detectable life forms. Until now, most numerical climate studies on this topic have focused on the conditions necessary to maintain oceans, but not to form them in the first place. Here we use the three-dimensional Generic Planetary Climate Model (PCM), historically known as the LMD Generic Global Climate Model (GCM), to simulate water-dominated planetary atmospheres around different types of Main-Sequence stars. The simulations are designed to reproduce the conditions of early ocean formation on rocky planets due to the condensation of the primordial water reservoir at the end of the magma ocean phase. We show that the incoming stellar radiation (ISR) required to form oceans by condensation is always drastically lower than that required to vaporize oceans. We introduce a Water Condensation Limit, which lies at significantly lower ISR than the inner edge of the HZ calculated with three-dimensional numerical climate simulations. This difference is due to a behavior change of water clouds, from low-altitude dayside convective clouds to high-altitude nightside stratospheric clouds. Finally, we calculated transit spectra, emission spectra and thermal phase curves of TRAPPIST-1b, c and d with H2O-rich atmospheres, and compared them to CO2 atmospheres and bare rock simulations. We show using these observables that JWST has the capability to probe steam atmospheres on low-mass planets, and could possibly test the existence of nightside water clouds.

Authors:J. Mah, B. Bitsch, I. Pascucci, T. Henning

Abstract: The origin of the elevated C/O ratios in discs around late M dwarfs compared to discs around solar-type stars is not well understood. Here we endeavour to reproduce the observed differences in the disc C/O ratios as a function of stellar mass using a viscosity-driven disc evolution model and study the corresponding atmospheric composition of planets that grow inside the water-ice line in these discs. We carried out simulations using a coupled disc evolution and planet formation code that includes pebble drift and evaporation. We used a chemical partitioning model for the dust composition in the disc midplane. Inside the water-ice line, the disc's C/O ratio initially decreases to sub-stellar due to the inward drift and evaporation of water-ice-rich pebbles before increasing again to super-stellar values due to the inward diffusion of carbon-rich vapour. We show that this process is more efficient for very low-mass stars compared to solar-type stars due to the closer-in ice lines and shorter disc viscous timescales. In high-viscosity discs, the transition from sub-stellar to super-stellar takes place faster due to the fast inward advection of carbon-rich gas. Our results suggest that planets accreting their atmospheres early (when the disc C/O is still sub-stellar) will have low atmospheric C/O ratios, while planets that accrete their atmospheres late (when the disc C/O has become super-stellar) can obtain high C/O ratios. Our model predictions are consistent with observations, under the assumption that all stars have the same metallicity and chemical composition, and that the vertical mixing timescales in the inner disc are much shorter than the radial advection timescales. This further strengthens the case for considering stellar abundances alongside disc evolution in future studies that aim to link planet (atmospheric) composition to disc composition.

Authors:Kangrou Guo, Eiichiro Kokubo

Abstract: We investigate the orbital evolution of planetesimals in the inner disk in the presence of nebula gas and a (proto-) cold Jupiter. By varying the mass, eccentricity, and semi-major axis of the planet, we study the dependence of the relative velocities of the planetesimals on these parameters. For classic small planetesimals ($10^{16}-10^{20} $g) whose mutual gravitational interaction is negligible, gas drag introduces a size-dependent alignment of orbits and keeps the relative velocity low for similar-size bodies, while preventing orbital alignment for different-size planetesimals. Regardless of the location and the mass ratio of the planetesimals, increasing the mass and eccentricity or decreasing the orbital distance of the planet always leads to higher relative velocities of planetesimals. However, for massive planetesimals, the interplay of viscous stirring, gas damping, and secular perturbation results in lower velocity dispersion of equal-size planetesimals when the planet is more massive or when it is located on a closer or more eccentric orbit. The random velocities of such planetesimals remain almost unperturbed when the planet is located beyond Jupiter's current orbit, or when it is less massive or less eccentric than Jupiter. Unlike small planetesimals, such large planetesimals can grow in a runaway fashion as in the unperturbed case. Our results imply that the presence of a cold Jupiter does not impede the formation of inner rocky planets through planetesimal accretion, provided that the planetesimals are initially large.

Authors:B. Klein, F. Debras, J. -F. Donati, T. Hood, C. Moutou, A. Carmona, M. Ould-elkhim, B. Bézard, B. Charnay, P. Fouqué, A. Masson, S. Vinatier, C. Baruteau, I. Boisse, X. Bonfils, A. Chiavassa, X. Delfosse, W. Dethier, G. Hebrard, F. Kiefer, J. Leconte, E. Martioli, V. Parmentier, P. Petit, W. Pluriel, F. Selsis, L. Teinturier, P. Tremblin, M. Turbet, O. Venot

Abstract: Atmospheric characterisation of exoplanets from the ground is an actively growing field of research. In this context we have created the ATMOSPHERIX consortium: a research project aimed at characterizing exoplanets atmospheres using ground-based high resolution spectroscopy. This paper presents the publicly-available data analysis pipeline and demonstrates the robustness of the recovered planetary parameters from synthetic data. Simulating planetary transits using synthetic transmission spectra of a hot Jupiter that were injected into real SPIRou observations of the non-transiting system Gl 15 A, we show that our pipeline is successful at recovering the planetary signal and input atmospheric parameters. We also introduce a deep learning algorithm to optimise data reduction which proves to be a reliable, alternative tool to the commonly used principal component analysis. We estimate the level of uncertainties and possible biases when retrieving parameters such as temperature and composition and hence the level of confidence in the case of retrieval from real data. Finally, we apply our pipeline onto two real transits of HD~189733 b observed with SPIRou and obtain similar results than in the literature. In summary, we have developed a publicly available and robust pipeline for the forthcoming studies of the targets to be observed in the framework of the ATMOSPHERIX consortium, which can easily be adapted to other high resolution instruments than SPIRou (e.g. VLT-CRIRES, MAROON-X, ELT-ANDES)

Authors:F. Debras, B. Klein, J. -F. Donati, T. Hood, C. Moutou, A. Carmona, B. Charnay, B. Bézard, P. Fouqué, A. Masson, S. Vinatier, C. Baruteau, I. Boisse, X. Bonfils, A. Chiavassa, X. Delfosse, G. Hebrard, J. Leconte, E. Martioli, M. Ould-elkhim, V. Parmentier, P. Petit, W. Pluriel, F. Selsis, L. Teinturier, P. Tremblin, M. Turbet, O. Venot

Abstract: In a companion paper, we introduced a publicly-available pipeline to characterise exoplanet atmospheres through high-resolution spectroscopy. In this paper, we use this pipeline to study the biases and degeneracies that arise in atmospheric characterisation of exoplanets in near-infrared ground-based transmission spectroscopy. We inject synthetic planetary transits into sequences of SPIRou spectra of the well known M dwarf star Gl 15 A, and study the effects of different assumptions on the retrieval. We focus on (i) mass and radius uncertainties, (ii) non isothermal vertical profiles and (iii) identification and retrieval of multiple species. We show that the uncertainties on mass and radius should be accounted for in retrievals and that depth-dependent temperature information can be derived from high-resolution transmission spectroscopy data. Finally, we discuss the impact of selecting wavelength orders in the retrieval and the issues that arise when trying to identify a single species in a multi-species atmospheric model. This analysis allows us to understand better the results obtained through transmission spectroscopy and their limitations in preparation to the analysis of actual SPIRou data.

Authors:Christopher Lee

Abstract: Crater mapping using neural networks and other automated methods has increased recently with automated Crater Detection Algorithms (CDAs) applied to planetary bodies throughout the solar system. A recent publication by Benedix et al. (2020) showed high performance at small scales compared to similar automated CDAs but with a net positive diameter bias in many crater candidates. I compare the publicly available catalogs from Benedix et al. (2020) and Lee & Hogan (2021) and show that the reported performance is sensitive to the metrics used to test the catalogs. I show how the more permissive comparison methods indicate a higher CDA performance by allowing worse candidate craters to match ground-truth craters. I show that the Benedix et al. (2020) catalog has a substantial performance loss with increasing latitude and identify an image projection issue that might cause this loss. Finally, I suggest future applications of neural networks in generating large scientific datasets be validated using secondary networks with independent data sources or training methods.

Authors:Kevin Ollmann, Sebastian Wolf, Moritz Lietzow, Thomas A. Stuber

Abstract: Hot exozodiacal dust (HEZD) found around main-sequence stars through interferometric observations in the photometric bands H to L is located close to the dust sublimation radius, potentially at orbital radii comparable to those of close-in exoplanets. Consequently, HEZD has a potential influence on the analysis of the scattered-light polarization of close-in exoplanets and vice versa. We analyze the impact of HEZD on the polarimetric characterization of close-in exoplanets. This study is motivated in particular by the recently proven feasibility of exoplanet polarimetry. Applying the 3D Monte Carlo radiative transfer code POLARIS in an extended and optimized version for radiative transfer in exoplanetary atmospheres and an analytical tool for modeling the HEZD, we simulated and compared the polarization characteristics of the wavelength-dependent scattered-light polarization of HEZD and close-in exoplanets. The varied parameters are the planetary phase angle ($0^\circ-180^\circ$), the dust grain radius ($0.02\ \mu$m $- \ 10\ \mu$m), the HEZD mass ($10^{-10}$$\rm{M}_{\oplus}$ $-\ 10^{-8}$$\rm{M}_{\oplus}$), the orbital inclination ($0^\circ-90^\circ$), the composition of the planetary atmosphere (Mie and Rayleigh scattering atmosphere), the orbital radius of the HEZD ($0.02$ au $-\ 0.4$ au), and the planetary orbital radius ($0.01$ au $-\ 0.05$ au). The dust grain radius has the strongest influence on the polarimetric analysis due to its significant impact on the wavelength-dependent polarization characteristics and the total order of magnitude of the scattered-light polarization. In certain scenarios, the scattered-light polarization of the HEZD even exceeds that of the close-in exoplanet.

Authors:M. Damasso, J. Rodrigues, A. Castro-González, B. Lavie, J. Davoult, M. R. Zapatero Osorio, J. Dou, S. G. Sousa, J. E. Owen, P. Sossi, V. Adibekyan, H. Osborn, Z. Leinhardt, Y. Alibert, C. Lovis, E. Delgado Mena, A. Sozzetti, S. C. C. Barros, D. Bossini, C. Ziegler, D. R. Ciardi, E. C. Matthews, P. J. Carter, J. Lillo-Box, A. Suárez Mascareño, S. Cristiani, F. Pepe, R. Rebolo, N. C. Santos, C. Allende Prieto, S. Benatti, F. Bouchy, C. Briceño, P. Di Marcantonio, V. D'Odorico, X. Dumusque, J. A. Egger, D. Ehrenreich, J. Faria, P. Figueira, R. Génova Santos, E. J. Gonzales, J. I. González Hernández, N. Law, G. Lo Curto, A. W. Mann, C. J. A. P. Martins, A. Mehner, G. Micela, P. Molaro, N. J. Nunes, E. Palle, E. Poretti, J. E. Schlieder, S. Udry

Abstract: We followed-up with ESPRESSO the K0V star HIP 29442 (TOI-469), already known to host a validated sub-Neptune companion TOI-469.01. We aim to verify the planetary nature of TOI-469.01. We modelled radial velocity and photometric time series to measure the dynamical mass, radius, and ephemeris, and to characterise the internal structure and composition of TOI-469.01. We confirmed the planetary nature of TOI-469.01. Thanks to ESPRESSO we discovered two additional close-in companions. We also detected their low signal-to-noise transit signals in the TESS light curve. HIP 29442 is a compact multi-planet system, and the three planets have orbital periods $P_{\rm orb, b}=13.63083\pm0.00003$, $P_{\rm orb, c}=3.53796\pm0.00003$, and $P_{\rm orb, d}=6.42975^{+0.00009}_{-0.00010}$ days, and we measured their masses with high precision: $m_{\rm p, b}=9.6\pm0.8~M_{\oplus}$, $m_{\rm p, c}=4.5\pm0.3~M_{\oplus}$, and $m_{\rm p, d}=5.1\pm0.4~M_{\oplus}$. We measured radii and bulk densities of all the planets (the 3$\sigma$ confidence intervals are shown in parenthesis): $R_{\rm p, b}=3.48^{+0.07 (+0.19)}_{-0.08 (-0.28)} ~R_{\oplus}$ and $\rho_{\rm p, b}=1.3\pm0.2 (0.3) g~cm^{-3}$; $R_{\rm p, c}=1.58^{+0.10 (+0.30)}_{-0.11 (-0.34)}~R_{\oplus}$ and $\rho_{\rm p, c}=6.3^{+1.7 (+6.0)}_{-1.3 (-2.7)} g~cm^{-3}$; $R_{\rm p, d}=1.37\pm0.11^{(+0.32)}_{(-0.43)}~R_{\oplus}$ and $\rho_{\rm p, d}=11.0^{+3.4 (+21.0)}_{-2.4 (-6.3)} g~cm^{-3}$. We used the more conservative 3$\sigma$ confidence intervals for the radii as input to the interior structure modelling. We find that HIP 29442 $b$ appears as a typical sub-Neptune, likely surrounded by a gas layer of pure H-He with a mass of $0.27^{+0.24}_{-0.17} M_{\oplus}$ and a thickness of $1.4\pm0.5 R_{\oplus}$. For the innermost companions HIP 29442 $c$ HIP 29442 $d$, the model supports an Earth-like composition.

Authors:Lily Ishizaki, Shogo Tachibana, Tamami Okamoto, Daiki Yamamoto, Shigeru Ida

Abstract: Dust particles in protoplanetary disks experience various chemical reactions under different physicochemical conditions through their accretion and diffusion, which results in the radial chemical gradient of dust. We performed three-dimensional Monte Carlo simulations to evaluate the dust trajectories and the progress of fictitious irreversible reactions, of which kinetics is expressed by the Johnson-Mehl-Avrami equation. The distribution of the highest temperature that each particle experiences before the degree of reaction exceeds a certain level shows the log-normal distribution, and its mode temperature was used as the effective reaction temperature. Semi-analytical prediction formulas of the effective reaction temperature and its dispersion were derived by comparing a reaction timescale with a diffusive transport timescale of dust as a function of the reaction parameters and the disk parameters. The formulas reproduce the numerical results of the effective reaction temperatures and their dispersions within 5.5 and 24 %, respectively, in a wide temperature range (200-1400 K). We applied the formulas for the crystallization of amorphous silicate dust and its oxygen isotope exchange with the H2O vapor based on the experimentally determined kinetics. For sub-micron sized amorphous forsterite dust, the predicted effective reaction temperature for the oxygen isotope exchange was lower than that of crystallization without overlap even considering their dispersions. This suggests that the amorphous silicate dust in the protosolar disk could exchange their oxygen isotopes efficiently with the 16O-poor H2O vapor, resulting in the distinct oxygen isotope compositions from the Sun.

Authors:Ian R. Edmonds

Abstract: This paper explores a possible linkage between solar motion about the solar system center of mass and the quasi-periodicity evident in the pressure and temperature of planet atmospheres. We establish that dominant mid frequency range periodicity in planet atmospheres corresponds closely to the harmonic series 39.5/n = TA/n years where n = 2, 3, 4, etc. We establish that the period TA = 39.5 years is the interval between acceleration impulses experienced by the Sun as it passes close to the solar system center of mass and that the time sequence of impulses generates the spectral harmonic series TA/n that is observed in the periodicity of climate indices like the North Atlantic Oscillation and the Quasi Biennial Oscillation. We develop a model of a simple harmonic oscillator responding to periodic acceleration impulses and show that the response duplicates several features of the Quasi Biennial Oscillation. We conclude that oscillatory phenomena observed in solar activity and in planet atmosphere variability could be due to the response of the various natural oscillatory modes to impulsive Sun acceleration associated with planetary motion.

Authors:Barbara Ercolano LMU, Munich, Giovanni Picogna LMU, Munich, Kristina Monsch CfA

Abstract: Photoevaporation from high energy stellar radiation has been thought to drive the dispersal of protoplanetary discs. Different theoretical models have been proposed, but their predictions diverge in terms of the rate and modality at which discs lose their mass, with significant implications for the formation and evolution of planets. In this paper we use disc population synthesis models to interpret recent observations of the lowest accreting protoplanetary discs, comparing predictions from EUV-driven, FUV-driven and X-ray driven photoevaporation models. We show that the recent observational data of stars with low accretion rates (low accretors) point to X-ray photoevaporation as the preferred mechanism driving the final stages of protoplanetary disc dispersal. We also show that the distribution of accretion rates predicted by the X-ray photoevaporation model is consistent with observations, while other dispersal models tested here are clearly ruled out.

Authors:Patrick G. J. Irwin, Jack Dobinson, Arjuna James. Michael H. Wong, Leigh N. Fletcher, Michael T. Roman, Nicholas A. Teanby, Daniel Toledo, Glenn S. Orton, Santiago Perez-Hoyos, Agustin Sanchez-Lavega, Lawrence Sromovsky, Amy A. Simon, Raul Morales-Juberias, Imke de Pater, Statia L. Cook

Abstract: Previous observations of dark vortices in Neptune's atmosphere, such as Voyager-2's Great Dark Spot, have been made in only a few, broad-wavelength channels, which has hampered efforts to pinpoint their pressure level and what makes them dark. Here, we present Very Large Telescope (Chile) MUSE spectrometer observations of Hubble Space Telescope's NDS-2018 dark spot, made in 2019. These medium-resolution 475 - 933 nm reflection spectra allow us to show that dark spots are caused by a darkening at short wavelengths (< 700 nm) of a deep ~5-bar aerosol layer, which we suggest is the H$_2$S condensation layer. A deep bright spot, named DBS-2019, is also visible on the edge of NDS-2018, whose spectral signature is consistent with a brightening of the same 5-bar layer at longer wavelengths (> 700 nm). This bright feature is much deeper than previously studied dark spot companion clouds and may be connected with the circulation that generates and sustains such spots.

Authors:Alan P. Boss, Shubham Kanodia

Abstract: Recent discoveries of gas giant exoplanets around M-dwarfs (GEMS) from transiting and radial velocity (RV) surveys are difficult to explain with core-accretion models. We present here a homogeneous suite of 162 models of gravitationally unstable gaseous disks. These models represent an existence proof for gas giants more massive than 0.1 Jupiter masses to form by the gas disk gravitational instability (GDGI) mechanism around M-dwarfs for comparison with observed exoplanet demographics and protoplanetary disk mass estimates for M-dwarf stars. We use the Enzo 2.6 adaptive mesh refinement (AMR) 3D hydrodynamics code to follow the formation and initial orbital evolution of gas giant protoplanets in gravitationally unstable gaseous disks in orbit around M-dwarfs with stellar masses ranging from 0.1 $M_\odot$ to 0.5 $M_\odot$. The gas disk masses are varied over a range from disks that are too low in mass to form gas giants rapidly to those where numerous gas giants are formed, therefore revealing the critical disk mass necessary for gas giants to form by the GDGI mechanism around M-dwarfs. The disk masses vary from 0.01 $M_\odot$ to 0.05 $M_\odot$ while the disk to star mass ratios explored range from 0.04 to 0.3. The models have varied initial outer disk temperatures (10 K to 60 K) and varied levels of AMR grid spatial resolution, producing a sample of expected gas giant protoplanets for each star mass. Broadly speaking, disk masses of at least 0.02 $M_\odot$ are needed for the GDGI mechanism to form gas giant protoplanets around M-dwarfs.

Authors:Ares Osborn, David J. Armstrong, Jorge Fernández Fernández, Henrik Knierim, Vardan Adibekyan, Karen A. Collins, Elisa Delgado-Mena, Malcolm Fridlund, João Gomes da Silva, Coel Hellier, David G. Jackson, George W. King, Jorge Lillo-Box, Rachel A. Matson, Elisabeth C. Matthews, Nuno C. Santos, Sérgio G. Sousa, Keivan G. Stassun, Thiam-Guan Tan, George R. Ricker, Roland Vanderspek, David W. Latham, Sara Seager, Joshua N. Winn, Jon M. Jenkins, Daniel Bayliss, Luke G. Bouma, David R. Ciardi, Kevin I. Collins, Knicole D. Colón, Ian J. M. Crossfield, Olivier D. S. Demangeon, Rodrigo F. Díaz, Caroline Dorn, Xavier Dumusque, Marcelo Aron Fetzner Keniger, Pedro Figueira, Tianjun Gan, Robert F. Goeke, Andreas Hadjigeorghiou, Faith Hawthorn, Ravit Helled, Steve B. Howell, Louise D. Nielsen, Hugh P. Osborn, Samuel N. Quinn, Ramotholo Sefako, Avi Shporer, Paul A. Strøm, Joseph D. Twicken, Andrew Vanderburg, Peter J. Wheatley

Abstract: To date, thousands of planets have been discovered, but there are regions of the orbital parameter space that are still bare. An example is the short period and intermediate mass/radius space known as the Neptunian desert, where planets should be easy to find but discoveries remain few. This suggests unusual formation and evolution processes are responsible for the planets residing here. We present the discovery of TOI-332 b, a planet with an ultra-short period of $0.78$ d that sits firmly within the desert. It orbits a K0 dwarf with an effective temperature of $5251 \pm 71$ K. TOI-332 b has a radius of $3.20^{+0.16}_{-0.12}$ R$_{\oplus}$, smaller than that of Neptune, but an unusually large mass of $57.2 \pm 1.6$ M$_{\oplus}$. It has one of the highest densities of any Neptune-sized planet discovered thus far at $9.6^{+1.1}_{-1.3}$ gcm$^{-3}$. A 4-layer internal structure model indicates it likely has a negligible hydrogen-helium envelope, something only found for a small handful of planets this massive, and so TOI-332 b presents an interesting challenge to planetary formation theories. We find that photoevaporation cannot account for the mass loss required to strip this planet of the Jupiter-like envelope it would have been expected to accrete. We need to look towards other scenarios, such as high-eccentricity migration, giant impacts, or gap opening in the protoplanetary disc, to try and explain this unusual discovery.

Authors:Kazuhiro D. Kanagawa, Tomohiro Ono, Munetake Momose

Abstract: A planet embedded in a protoplanetary disk produces a gap by disk-planet interaction. It also generates velocity perturbation of gas, which can also be observed as deviations from the Keplerian rotation in the channel map of molecular line emission, called kinematic planetary features. These observed signatures provide clues to determine the mass of the planet. We investigated the features induced by the planet with an inclined orbit through three-dimensional hydrodynamic simulations. We found that a smaller planet, with the inclination being $\sim 10^{\circ}$ -- $20^{\circ}$, can produce kinematic features as prominent as those induced by the massive coplanar planet. Despite the kinematic features being similar, the gap is shallower and narrower as compared with the case in which the kinematic features are formed by the coplanar planet. We also found that the kinematic features induced by the inclined planet were fainter for rarer CO isotopologues because the velocity perturbation is weaker at the position closer to the midplane, which was different in the case with a coplanar massive planet. This dependence on the isotopologues is distinguished if the planet has the inclined orbit. We discussed two observed kinematic features in the disk of HD 163296. We concluded that the kink observed at 220 au can be induced by the inclined planet, while the kink at 67 au is consistent to that induced by the coplanar planet.

Authors:Olivier Poch, Antoine Pommerol, Nicolas Fray, Bastian Gundlach

Abstract: In order to understand the origin and evolution of comets, one must decipher the processes that formed and processed cometary ice and dust. Cometary materials have diverse physical and chemical properties and are mixed in various ways. Laboratory experiments are capable of producing simple to complex analogues of comet-like materials, measuring their properties, and simulating the processes by which their compositions and structures may evolve. The results of laboratory experiments are essential for the interpretations of comet observations and complement theoretical models. They are also necessary for planning future missions to comets. This chapter presents an overview of past and ongoing laboratory experiments exploring how comets were formed and transformed, from the nucleus interior and surface, to the coma. Throughout these sections, the pending questions are highlighted, and the perspectives and prospects for future experiments are discussed.

Authors:L. Delrez, A. Leleu, A. Brandeker, M. Gillon, M. J. Hooton, A. Collier Cameron, A. Deline, A. Fortier, D. Queloz, A. Bonfanti, V. Van Grootel, T. G. Wilson, J. A. Egger, Y. Alibert, R. Alonso, G. Anglada, J. Asquier, T. Bárczy, D. Barrado y Navascues, S. C. C. Barros, W. Baumjohann, M. Beck, T. Beck, W. Benz, N. Billot, X. Bonfils, L. Borsato, C. Broeg, M. Buder, J. Cabrera, V. Cessa, S. Charnoz, Sz. Csizmadia, P. E. Cubillos, M. B. Davies, M. Deleuil, O. D. S. Demangeon, B. -O. Demory, D. Ehrenreich, A. Erikson, L. Fossati, M. Fridlund, D. Gandolfi, M. Güdel, J. Hasiba, S. Hoyer, K. G. Isaak, J. M. Jenkins, L. L. Kiss, J. Laskar, D. W. Latham, A. Lecavelier des Etangs, M. Lendl, C. Lovis, R. Luque, D. Magrin, P. F. L. Maxted, C. Mordasini, V. Nascimbeni, G. Olofsson, R. Ottensamer, I. Pagano, E. Pallé, G. Peter, G. Piotto, D. Pollacco, R. Ragazzoni, N. Rando, H. Rauer, I. Ribas, G. Ricker, N. C. Santos, G. Scandariato, S. Seager, D. Ségransan, A. E. Simon, A. M. S. Smith, S. G. Sousa, M. Steller, Gy. M. Szabó, N. Thomas, S. Udry, R. Vanderspek, J. Venturini, V. Viotto, N. A. Walton, J. N. Winn

Abstract: The TOI-178 system consists of a nearby late K-dwarf transited by six planets in the super-Earth to mini-Neptune regime, with orbital periods between 1.9 and 20.7 days. All planets but the innermost one form a chain of Laplace resonances. Mass estimates derived from a preliminary radial velocity (RV) dataset suggest that the planetary densities do not decrease in a monotonic way with the orbital distance to the star, contrary to what one would expect based on simple formation and evolution models. To improve the characterisation of this key system and prepare for future studies (in particular with JWST), we perform a detailed photometric study based on 40 new CHEOPS visits, one new TESS sector, as well as previously published CHEOPS, TESS, and NGTS data. First we perform a global analysis of the 100 transits contained in our data to refine the transit parameters of the six planets and study their transit timing variations (TTVs). We then use our extensive dataset to place constraints on the radii and orbital periods of potential additional transiting planets in the system. Our analysis significantly refines the transit parameters of the six planets, most notably their radii, for which we now obtain relative precisions $\lesssim$3%, with the exception of the smallest planet $b$ for which the precision is 5.1%. Combined with the RV mass estimates, the measured TTVs allow us to constrain the eccentricities of planets $c$ to $g$, which are found to be all below 0.02, as expected from stability requirements. Taken alone, the TTVs also suggest a higher mass for planet $d$ than the one estimated from the RVs, which had been found to yield a surprisingly low density for this planet. However, the masses derived from the current TTV dataset are very prior-dependent and further observations, over a longer temporal baseline, are needed to deepen our understanding of this iconic planetary system.

Authors:Shubham Kanodia, Matthias Y. He, Eric B. Ford, Sujit K. Ghosh, Angie Wolfgang

Abstract: Fundamental to our understanding of planetary bulk compositions is the relationship between their masses and radii, two properties that are often not simultaneously known for most exoplanets. However, while many previous studies have modeled the two-dimensional relationship between planetary mass and radii, this approach largely ignores the dependencies on other properties that may have influenced the formation and evolution of the planets. In this work, we extend the existing nonparametric and probabilistic framework of \texttt{MRExo} to jointly model distributions beyond two dimensions. Our updated framework can now simultaneously model up to four observables, while also incorporating asymmetric measurement uncertainties and upper limits in the data. We showcase the potential of this multi-dimensional approach to three science cases: (i) a 4-dimensional joint fit to planetary mass, radius, insolation, and stellar mass, hinting of changes in planetary bulk density across insolation and stellar mass; (ii) a 3-dimensional fit to the California Kepler Survey sample showing how the planet radius valley evolves across different stellar masses; and (iii) a 2-dimensional fit to a sample of Class-II protoplanetary disks in Lupus while incorporating the upper-limits in dust mass measurements. In addition, we employ bootstrap and Monte-Carlo sampling to quantify the impact of the finite sample size as well as measurement uncertainties on the predicted quantities. We update our existing open-source user-friendly \texttt{MRExo} \texttt{Python} package with these changes, which allows users to apply this highly flexible framework to a variety of datasets beyond what we have shown here.

Authors:Aditya Chopra, Aaron C Bell, William Fawcett, Rodd Talebi, Daniel Angerhausen, Atılım Güneş Baydin, Anamaria Berea, Nathalie A. Cabrol, Christopher Kempes, Massimo Mascaro

Abstract: Cloud computing offers an opportunity to run compute-resource intensive climate models at scale by parallelising model runs such that datasets useful to the exoplanet community can be produced efficiently. To better understand the statistical distributions and properties of potentially habitable planetary atmospheres we implemented a parallelised climate modelling tool to scan a range of hypothetical atmospheres.Starting with a modern day Earth atmosphere, we iteratively and incrementally simulated a range of atmospheres to infer the landscape of the multi-parameter space, such as the abundances of biological mediated gases (\ce{O2}, \ce{CO2}, \ce{H2O}, \ce{CH4}, \ce{H2}, and \ce{N2}) that would yield `steady state' planetary atmospheres on Earth-like planets around solar-type stars. Our current datasets comprises of \numatmospheres simulated models of exoplanet atmospheres and is available publicly on the NASA Exoplanet Archive. Our scalable approach of analysing atmospheres could also help interpret future observations of planetary atmospheres by providing estimates of atmospheric gas fluxes and temperatures as a function of altitude. Such data could enable high-throughput first-order assessment of the potential habitability of exoplanetary surfaces and sepcan be a learning dataset for machine learning applications in the atmospheric and exoplanet science domain.

Authors:K. Durga Prasad, Dibyendu Misra, Amitabh, Megha Bhatt, G. Ambily, Sachana Sathyan, Neeraj Srivastava, Anil Bhardwaj

Abstract: India's third Moon mission Chandrayaan 3 will deploy a lander and a rover at a high latitude location of the Moon enabling us to carry out first ever in-situ science investigations of such a pristine location that will potentially improve our understanding on primary crust formation and subsequent modification processes. The primary landing site (PLS), is situated at 69.367621 degS, 32.348126 degE. As a contingency, an alternate landing site (ALS) was also selected at nearly the same latitude but nearly 450 km west to PLS. In this work, a detailed study of the geomorphology, composition, and temperature characteristics of ALS has been carried out using the best-ever high resolution Chandrayaan 2 OHRC DEMs and Ortho images, datasets obtained from Chandrayaan 1 and on-going Lunar Reconnaissance Orbiter. For understanding the thermophysical behaviour, we used a well-established thermophysical model. We found that the Chandrayaan 3 ALS is characterised by a smooth topography with an elevated central part. The ALS is a scientifically interesting site with a high possibility of sampling ejecta materials from Tycho and Moretus. Based on the spectral and elemental analysis of the site, Fe is found to be near approx. 4.8 wt.%, with Mg approx. 5 wt.%, and Ca approx. 11 wt.%. Compositionally, ALS is similar to PLS with a highland soil composition. Spatial and diurnal variability of around 40 K and 175 K has been observed in the surface temperatures at ALS. Although belonging to similar location like PLS, ALS showed reduced daytime temperatures and enhanced night-time temperatures compared to PLS, indicating a terrain of distinctive thermophysical characteristics. Like PLS, ALS is also seems to be an interesting site for science investigations and Chandrayaan 3 is expected to provide new insights into the understanding of lunar science even if it happens to land in the alternate landing site.

Authors:Laurel Kaye, Shreyas Vissapragada, Maximilian N. Gunther, Suzanne Aigrain, Thomas Mikal-Evans, Eric L. N. Jensen, Hannu Parviainen, Francisco J. Pozuelos, Lyu Abe, Jack S. Acton, Abdelkrim Agabi, Douglas R. Alves, David R. Anderson, David J. Armstrong, Khalid Barkaoui, Oscar Barragan, Bjorn Benneke, Patricia T. Bo yd, Rafael Brahm, Ivan Bruni, Edward M. Bryant, Matthew R. Burleigh, Sarah L. Casewell, David Ciardi, Ryan Cloutier, Karen A. Collins, Kevin I. Collins, Dennis M. Conti, Ian J. M. Crossfield, Nicolas Crouzet, Tansu Daylan, Diana Dragomir, Georgina Dransfield, Daniel F abrycky, Michael Fausnaugh, Gabor Fuuresz, Tianjun Gan, Samuel Gill, Michael Gillon, Michael R Goad, Varoujan Gorjian, Michael Greklek-McKeon, Natalia Guerrero, Tristan Guillot, Emmanuel Jehin, J. S. Jenkins, Monika Lendl, Jacob Kamler, Stephen R. Kane, John F. Kielkopf, Michelle Kunimoto, Wenceslas Marie-Sainte, James McCormac, Djamel Mekarnia, Farisa Y. Morales, Maximiliano Moyano, Enric Palle, Vivien Parmentier, Howard M. Relles, Francois-Xavier Schmider, Richard P. Schwarz, S. Seager, Alexis M. S. Smith, Thiam-Guan Tan, Jake Taylor, Amaury H. M. J. Triaud, Joseph D. Twicken, Stephane Udry, J. I. Vines, Gavin Wang, Peter J. Wheatley, Joshua N. Winn

Abstract: We present ground and space-based photometric observations of TOI-270 (L231-32), a system of three transiting planets consisting of one super-Earth and two sub-Neptunes discovered by TESS around a bright (K-mag=8.25) M3V dwarf. The planets orbit near low-order mean-motion resonances (5:3 and 2:1), and are thus expected to exhibit large transit timing variations (TTVs). Following an extensive observing campaign using 8 different observatories between 2018 and 2020, we now report a clear detection of TTVs for planets c and d, with amplitudes of $\sim$10 minutes and a super-period of $\sim$3 years, as well as significantly refined estimates of the radii and mean orbital periods of all three planets. Dynamical modeling of the TTVs alone puts strong constraints on the mass ratio of planets c and d and on their eccentricities. When incorporating recently published constraints from radial velocity observations, we obtain masses of $M_{\mathrm{b}}=1.48\pm0.18\,M_\oplus$, $M_{c}=6.20\pm0.31\,M_\oplus$ and $M_{\mathrm{d}}=4.20\pm0.16\,M_\oplus$ for planets b, c and d, respectively. We also detect small, but significant eccentricities for all three planets : $e_\mathrm{b} =0.0167\pm0.0084$, $e_{c} =0.0044\pm0.0006$ and $e_{d} = 0.0066\pm0.0020$. Our findings imply an Earth-like rocky composition for the inner planet, and Earth-like cores with an additional He/H$_2$O atmosphere for the outer two. TOI-270 is now one of the best-constrained systems of small transiting planets, and it remains an excellent target for atmospheric characterization.

Authors:Max Goldberg, Daniel Fabrycky, David V. Martin, Simon Albrecht, Hans J. Deeg, Grzegorz Nowak

Abstract: Over a dozen transiting circumbinary planets have been discovered around eclipsing binaries. Transit detections are biased towards aligned planet and binary orbits, and indeed all of the known planets have mutual inclinations less than $4.5^{\circ}$. One path to discovering circumbinary planets with misaligned orbits is through eclipse timing variations (ETVs) of non-transiting planets. Borkovits et al. (2016) discovered ETVs on the 18.6 d binary Kepler-1660AB, indicative of a third body on a $\approx 236$ d period, with a misaligned orbit and a potentially planetary mass. Getley et al. (2017) agreed with the planetary hypothesis, arguing for a $7.7M_{\rm Jup}$ circumbinary planet on an orbit that is highly misaligned by $120^{\circ}$ with respect to the binary. In this paper, we obtain the first radial velocities of the binary. We combine these with an analysis of not only the ETVs but also the eclipse depth variations. We confirm the existence of a $239.5$ d circumbinary planet, but with a lower mass of $4.87M_{\rm Jup}$ and a coplanar orbit. The misaligned orbits proposed by previous authors are definitively ruled out by a lack of eclipse depth variations. Kepler-1660ABb is the first confirmed circumbinary planet found using ETVs around a main sequence binary.

Authors:Claire Marie Guimond, Oliver Shorttle, Sean Jordan, John F. Rudge

Abstract: From core to atmosphere, the oxidation states of elements in a planet shape its character. Oxygen fugacity (fO$_2$) is one parameter indicating these likely oxidation states. The ongoing search for atmospheres on rocky exoplanets benefits from understanding the plausible variety of their compositions, which depends strongly on their oxidation states -- and if derived from interior outgassing, on the fO$_2$ at the top of their silicate mantles. This fO$_2$ must vary across compositionally-diverse exoplanets, but for a given planet its value is unconstrained insofar as it depends on how iron (the dominant multivalent element) is partitioned between its 2+ and 3+ oxidation states. Here we focus on another factor influencing how oxidising a mantle is -- a factor modulating fO$_2$ even at fixed Fe$^{3+}$/Fe$^{2+}$ -- the planet's mineralogy. Only certain minerals (e.g., pyroxenes) incorporate Fe$^{3+}$. Having such minerals in smaller mantle proportions concentrates Fe$^{3+}$, increasing fO$_2$. Mineral proportions change within planets according to pressure, and between planets according to bulk composition. Constrained by observed host star refractory abundances, we calculate a minimum fO$_2$ variability across exoplanet mantles, of at least two orders of magnitude, due to mineralogy alone. This variability is enough to alter by a hundredfold the mixing ratio of SO$_2$ directly outgassed from these mantles. We further predict that planets orbiting high-Mg/Si stars are more likely to outgas detectable amounts of SO$_2$ and H$_2$O; and for low-Mg/Si stars, detectable CH$_4$, all else equal. Even absent predictions of Fe$^{3+}$ budgets, general insights can be obtained into how oxidising an exoplanet's mantle is.

Authors:M. Cerioni Instituto de Astronomía Teórica y Experimental, C. Beaugé Instituto de Astronomía Teórica y Experimental

Abstract: The K2-138 system hosts six planets and presents an interesting case study due to its distinctive dynamical structure. Its five inner planets are near a chain of 3/2 two-body mean-motion resonances, while the outermost body (planet {\it g}) is significantly detached, having a mean-motion ratio of $n_f/n_g \sim 3.3$ with its closest neighbor. We show that the orbit of $m_g$ is actually consistent with the first-order three-planet resonance (3P-MMR) characterized by the relation $2n_e - 4n_f + 3n_g = 0$ and is the first time a pure first-order 3P-MMR is found in a multi-planet system and tied to its current dynamical structure. Adequate values for the masses allow to trace the dynamical history of the system from an initial capture in a 6-planet chain (with $n_f/n_g$ in a 3/1 resonance), up to its current configuration due to tidal interactions over the age of the star. The increase in resonance offset with semi-major axis, as well as its large value for $n_f/n_g$ can be explained by the slopes of the pure three-planet resonances in the mean-motion ratio plane. The triplets slide outward over these curves when the innermost pair is pulled apart by tidal effects, in a \textit{pantograph-}like manner. The capture into the 3P-MMR is found to be surprisingly robust given similar masses for $m_g$ and $m_f$, and it is possible that the same effect may also be found in other compact planetary systems.

Authors:Benjamin J. Hord, Eliza M. -R. Kempton, Thomas Mikal-Evans, David W. Latham, David R. Ciardi, Diana Dragomir, Knicole D. Colón, Gabrielle Ross, Andrew Vanderburg, Zoe L. de Beurs, Karen A. Collins, Cristilyn N. Watkins, Jacob Bean, Nicolas B. Cowan, Tansu Daylan, Caroline V. Morley, Jegug Ih, David Baker, Khalid Barkaoui, Natalie M. Batalha, Aida Behmard, Alexander Belinski, Zouhair Benkhaldoun, Paul Benni, Krzysztof Bernacki, Allyson Bieryla, Avraham Binnenfeld, Pau Bosch-Cabot, François Bouchy, Valerio Bozza, Rafael Brahm, Lars A. Buchhave, Michael Calkins, Ashley Chontos, Catherine A. Clark, Ryan Cloutier, Marion Cointepas, Kevin I. Collins, Dennis M. Conti, Ian J. M. Crossfield, Fei Dai, Jerome P. de Leon, Georgina Dransfield, Courtney Dressing, Adam Dustor, Gilbert Esquerdo, Phil Evans, Sergio B. Fajardo-Acosta, Jerzy Fiołka, Raquel Forés-Toribio, Antonio Frasca, Akihiko Fukui, Benjamin Fulton, Elise Furlan, Tianjun Gan, Davide Gandolfi, Mourad Ghachoui, Steven Giacalone, Emily A. Gilbert, Michaël Gillon, Eric Girardin, Erica Gonzales, Ferran Grau Horta, Joao Gregorio, Michael Greklek-McKeon, Pere Guerra, J. D. Hartman, Coel Hellier, Krzysztof G. Hełminiak, Thomas Henning, Michelle L. Hill, Keith Horne, Andrew W. Howard, Steve B. Howell, Daniel Huber, Howard Isaacson, Giovanni Isopi, Emmanuel Jehin, Jon M. Jenkins, Eric L. N. Jensen, Marshall C. Johnson, Andrés Jordán, Stephen R. Kane, John F. Kielkopf, Vadim Krushinsky, Sławomir Lasota, Elena Lee, Pablo Lewin, John H. Livingston, Jack Lubin, Michael B. Lund, Franco Mallia, Christopher R. Mann, Giuseppe Marino, Nataliia Maslennikova, Bob Massey, Rachel Matson, Elisabeth Matthews, Andrew W. Mayo, Tsevi Mazeh, Kim K. McLeod, Edward J. Michaels, Teo Močnik, Mayuko Mori, Georgia Mraz, Jose A. Muñoz, Norio Narita, Louise Dyregaard Nielsen, Hugh Osborn, Enric Palle, Aviad Panahi, Riccardo Papini, Alex S. Polanski, Adam Popowicz, Francisco J. Pozuelos, Samuel N. Quinn, Don J. Radford, Phillip A. Reed, Howard M. Relles, Malena Rice, Paul Robertson, Joseph E. Rodriguez, Lee J. Rosenthal, Ryan A. Rubenzahl, Nicole Schanche, Joshua Schlieder, Richard P. Schwarz, Ramotholo Sefako, Avi Shporer, Alessandro Sozzetti, Gregor Srdoc, Chris Stockdale, Alexander Tarasenkov, Thiam-Guan Tan, Mathilde Timmermans, Eric B. Ting, Judah Van Zandt, JP Vignes, Ian Waite, Noriharu Watanabe, Lauren M. Weiss, Justin Wittrock, George Zhou, Carl Ziegler, Shay Zucker

Abstract: JWST has ushered in an era of unprecedented ability to characterize exoplanetary atmospheres. While there are over 5,000 confirmed planets, more than 4,000 TESS planet candidates are still unconfirmed and many of the best planets for atmospheric characterization may remain to be identified. We present a sample of TESS planets and planet candidates that we identify as "best-in-class" for transmission and emission spectroscopy with JWST. These targets are sorted into bins across equilibrium temperature $T_{\mathrm{eq}}$ and planetary radius $R{_\mathrm{p}}$ and are ranked by transmission and emission spectroscopy metric (TSM and ESM, respectively) within each bin. In forming our target sample, we perform cuts for expected signal size and stellar brightness, to remove sub-optimal targets for JWST. Of the 194 targets in the resulting sample, 103 are unconfirmed TESS planet candidates, also known as TESS Objects of Interest (TOIs). We perform vetting and statistical validation analyses on these 103 targets to determine which are likely planets and which are likely false positives, incorporating ground-based follow-up from the TESS Follow-up Observation Program (TFOP) to aid the vetting and validation process. We statistically validate 23 TOIs, marginally validate 33 TOIs to varying levels of confidence, deem 29 TOIs likely false positives, and leave the dispositions for 4 TOIs as inconclusive. 14 of the 103 TOIs were confirmed independently over the course of our analysis. We provide our final best-in-class sample as a community resource for future JWST proposals and observations. We intend for this work to motivate formal confirmation and mass measurements of each validated planet and encourage more detailed analysis of individual targets by the community.

Authors:L. Dover, S. C. Lowry, A. Rożek, B. Rozitis, S. L. Jackson, T. Zegmott, Yu. N. Krugly, I. N. Belskaya, A. Fitzsimmons, S. F. Green, C. Snodgrass, P. R. Weissman, M. Brozović, L. A. M. Benner, M. W. Busch, V. R. Ayvazian, V. Chiorny, R. Ya. Inasaridze, M. Krugov, S. Mykhailova, I. Reva, J. Hibbert

Abstract: We present a physical model and spin-state analysis of the potentially hazardous asteroid (23187) 2000 PN9. As part of a long-term campaign to make direct detections of the YORP effect, we collected optical lightcurves of the asteroid between 2006 and 2020. These observations were combined with planetary radar data to develop a detailed shape model which was used to search for YORP acceleration. We report that 2000 PN9 is a relatively large top-shaped body with a sidereal rotation period of 2.53216$\pm$0.00015 h. Although we find no evidence for rotational acceleration, YORP torques smaller than $\sim$10$^{-8}$$\,\rm rad/day^{2}$ cannot be ruled out. It is likely that 2000 PN9 is a YORP-evolved object, and may be an example of YORP equilibrium or self limitation.

Authors:Óscar Carrión-González, Jens Kammerer, Daniel Angerhausen, Felix Dannert, Antonio García Muñoz, Sascha P. Quanz, Olivier Absil, Charles A. Beichman, Julien H. Girard, Bertrand Mennesson, Michael R. Meyer, Karl R. Stapelfeldt, The LIFE Collaboration

Abstract: The next generation of space-based observatories will characterize the atmospheres of low-mass, temperate exoplanets with the direct-imaging technique. This will be a major step forward in our understanding of exoplanet diversity and the prevalence of potentially habitable conditions beyond the Earth. We compute a list of currently known exoplanets detectable with the mid-infrared Large Interferometer For Exoplanets (LIFE) in thermal emission. We also compute the list of known exoplanets accessible to a notional design of the Habitable Worlds Observatory (HWO), observing in reflected starlight. With a pre-existing method, we processed the NASA Exoplanet Archive and computed orbital realizations for each known exoplanet. We derived their mass, radius, equilibrium temperature, and planet-star angular separation. We used the LIFEsim simulator to compute the integration time ($t_{int}$) required to detect each planet with LIFE. A planet is considered detectable if a broadband signal-to-noise ratio $S/N$=7 is achieved over the spectral range $4-18.5\mu$m in $t_{int}\leq$100 hours. We tested whether the planet is accessible to HWO in reflected starlight based on its notional inner and outer working angles, and minimum planet-to-star contrast. LIFE's reference configuration (four 2-m telescopes with 5% throughput and a nulling baseline between 10-100 m) can detect 212 known planets within 20 pc. Of these, 55 are also accessible to HWO in reflected starlight, offering a unique opportunity for synergies in atmospheric characterization. LIFE can also detect 32 known transiting exoplanets. Furthermore, 38 LIFE-detectable planets orbit in the habitable zone, of which 13 with $M_p<5M_\oplus$ and 8 with $5M_\oplus<M_p<10M_\oplus$. LIFE already has enough targets to perform ground-breaking analyses of low-mass, habitable-zone exoplanets, a fraction of which will also be accessible to other instruments.

Authors:Cheng Chen, Rebecca G. Martin, C. J. Nixon

Abstract: We investigate the orbital stability of a tilted circumbinary planetary system with three giant planets. The planets are spaced by a constant number ($\Delta$) of mutual Hill radii in the range $\Delta=3.4-12.0$ such that the period ratio of the inner pair is the same as the outer pair. A tilted circumbinary planetary system can be unstable even if the same system around a coplanar binary is stable. For an equal mass binary, we find that the stability of a three-planet system is qualitatively similar to that of a two-planet system, but the three-planet system is more unstable in mean motion resonance regions. For an unequal mass binary, there is significantly more instability in the three-planet system as the inner planets can undergo von-Zeipel-Kozai-Lidov oscillations. Generally in unstable systems, the inner planets are more likely to be ejected than the outer planets. The most likely unstable outcome for closely spaced systems, with $\Delta \lesssim 8$, is a single remaining stable planet. For more widely separated systems, $\Delta \gtrsim 8$, the most likely unstable outcome is two stable planets, only one being ejected. An observed circumbinary planet with significant eccentricity may suggest that it was formed from an unstable system. Consequently, a binary can host three tilted giant planets if the binary stars are close to equal mass and provided that the planets are well spaced and not close to a mean motion resonance.

Authors:J. P. Sindel, Ch. Helling, D. Gobrecht, K. L. Chubb, L. Decin

Abstract: Context. Clouds seem unavoidable in cool and dense environments, and hence, are necessary to explain observations of exoplanet atmospheres, most recently of WASP 96b with JWST. Understanding the formation of cloud condensation nuclei in non-terrestrial environments is therefore crucial to develop accurate models to interpret present and future observations. Aims. The goal of the paper is to support observations with infrared spectra for (TiO2)N clusters in order to study cloud formation in exoplanet atmospheres. Methods. Vibrational frequencies are derived from quantum-chemical calculations for 123 (TiO2)-clusters and their isomers, and line-broadening mechanisms are evaluated. Cluster spectra are calculated for several atmospheric levels for two example exoplanet atmospheres (WASP 121b-like and WASP 96b-like) to identify possible spectral fingerprints for cloud formation. Results. Rotational motion of and transitions in the clusters cause significant line broadening, so that individual vibrational lines are broadened beyond the spectral resolution of the medium resolution mode of the JWST mid-infrared instrument MIRI at R = 3000. However, each individual cluster isomer exhibits a "fingerprint" IR spectrum. In particular, larger (TiO2)-clusters have distinctly different spectra from smaller clusters. Morning and evening terminator for the same planet can exhibit different total absorbances due to different cluster sizes being more abundant. Conclusions. The largest (TiO2)-clusters are not necessarily the most abundant (TiO2)-clusters in the high-altitude regions of ultra-hot Jupiters, and the different cluster isomers will contribute to the local absorbance. Planets with a considerable day-night asymmetry will be most suitable to search for (TiO2)-cluster isomers in order to improve cloud formation modelling.

Authors:Iva Vilović, Dirk Schulze-Makuch, René Heller

Abstract: Essential insights on the characterization and quality of a detectable biosphere are gained by analyzing the effects of its environmental parameters. We compiled environmental and biological properties of the Phanerozoic Eon from various published data sets and conducted a correlation analysis to assess variations in parameters relevant to the habitability of Earth's biosphere. We showed that environmental parameters such as oxygen, global average surface temperatures, runoff rates and carbon dioxide are interrelated and play a key role in the changes of biomass and biodiversity. We showed that there were several periods with a highly thriving biosphere, with one even surpassing present day biodiversity and biomass. Those periods were characterized by increased oxygen levels and global runoff rates, as well as moderate global average surface temperatures, as long as no large or rapid positive and/or negative temperature excursions occurred. High oxygen contents are diagnostic of biomass production by continental plant life. We find that exceptionally high oxygen levels can at least in one instance compensate for decreased relative humidities, providing an even more habitable environment compared to today. Beyond Earth, these results will help us to understand how environmental parameters affect biospheres on extrasolar planets and guide us in our search for extraterrestrial life.

Authors:Mario Damiano, Renyu Hu, Bertrand Mennesson

Abstract: Direct-imaging observations of terrestrial exoplanets will enable their atmospheric characterization and habitability assessment. Considering the Earth, the key atmospheric signatures for the biosphere is O$_2$ and the photochemical product O$_3$. However, this O$_2$-O$_3$ biosignature is not detectable in the visible wavelengths for most of the time after the emergence of oxygenic photosynthesis life (i.e., the Proterozoic Earth). Here we demonstrate spectroscopic observations in the ultraviolet wavelengths for detecting and characterizing O$_2$ and O$_3$ in Proterozoic Earth-like planets, using ExoReL$^\Re$. For an O$_2$ mixing ratio 2 to 3 orders of magnitude less than the present-day Earth, and an O$_3$ mixing ratio of $10^{-7}-10^{-6}$, we find that O$_3$ can be detected and its mixing ratio can be measured precisely (within $~1$ order of magnitude) in the ultraviolet ($0.25-0.4\ \mu$m) in addition to visible-wavelength spectroscopy. With modest spectral resolution ($R=7$) and S/N ($\sim10$) in the ultraviolet, the O$_3$ detection is robust against other potential gases absorbing in the ultraviolet (e.g., H$_2$S and SO$_2$), as well as the short-wavelength cutoff between 0.2 and 0.25 $\mu$m. While the O$_3$ detection does not rely on the near-infrared spectra, extending the wavelength coverage to the near-infrared ($1-1.8\ \mu$m) would provide essential information to interpret the O$_3$ biosignature, including the mixing ratio of H$_2$O, the cloud pressure, as well as the determination of the dominant gas of the atmosphere. The ultraviolet and near-infrared capabilities should thus be evaluated as critical components for future missions aiming at imaging and characterizing terrestrial exoplanets, such as the Habitable Worlds Observatory.

Authors:Roy T. Forestano, Konstantin T. Matchev, Katia Matcheva, Eyup B. Unlu

Abstract: The next generation of telescopes will yield a substantial increase in the availability of high-resolution spectroscopic data for thousands of exoplanets. The sheer volume of data and number of planets to be analyzed greatly motivate the development of new, fast and efficient methods for flagging interesting planets for reobservation and detailed analysis. We advocate the application of machine learning (ML) techniques for anomaly (novelty) detection to exoplanet transit spectra, with the goal of identifying planets with unusual chemical composition and even searching for unknown biosignatures. We successfully demonstrate the feasibility of two popular anomaly detection methods (Local Outlier Factor and One Class Support Vector Machine) on a large public database of synthetic spectra. We consider several test cases, each with different levels of instrumental noise. In each case, we use ROC curves to quantify and compare the performance of the two ML techniques.

Authors:Carolina Charalambous, Jean Teyssandier, Anne-Sophie Libert

Abstract: These last years several Systems with Tightly packed Inner Planets in the super-Earth mass regime have been discovered harboring chains of resonances. It is generally believed that planet pairs get trapped in MMR during the migration phase in the protoplanetary disk, while the tides raised by the host star provide a source of dissipation on very long timescales. In this work, we aim to study the departure from exact commensurabilities observed among the STIPs which harbor 3-planet resonances and analyze how tides play an important role in shaping the resonance offsets for the STIPs. We analyzed the resonance offsets between adjacent pairs for five multi-planetary systems, namely Kepler-80, Kepler-223, K2-138, TOI-178, and TRAPPIST-1, highlighting the existence of different trends in the offsets. On the one hand, we derived analytical estimates for the offsets, which confirm that the departure of the planetary pairs from the nominal MMRs are due to the 3-planet resonant dynamics. On the other hand, we performed N-body simulations including both orbital migration and tidal dissipation from the host star with simple prescriptions in order to test the effectiveness of this mechanism at shaping the observed trend in the offsets, focusing our study on the preservation of the resonant patterns in the different systems with the same general setup. We found that the trends in the offsets of the five detected systems can be produced by tidal damping effects, regardless of the considered value for the tidal factor. It is a robust mechanism that relaxes the system towards equilibrium while efficiently moving it along 3-planet resonances, which induces the observed resonance offset for each planet pair. In addition, we showed that for Kepler-80, K2-138, and TOI-178, the amplitudes of the resonant offsets can also be reproduced with appropriate tidal factor, for the estimated age of the systems.

Authors:Christian D. Tate, Julie A. Rathbun, Alexander G. Hayes, John R. Spencer, Madeline Pettine

Abstract: This study analyzes near-infrared measurements of Io, Jupiter's moon, observed over 170 nights from 2016 to early 2022 using the NASA Infrared Telescope Facility (IRTF). During this period, seven new volcanic outbursts, the most energetic volcanic events on Io, were discovered and characterized, increasing the total number of observed outburst events from 18 to 25. We also present simplified criteria for the thermal detection of an outburst, requiring it to be both confined to a specific location of Io and above a threshold intensity in the Lp-band (3.8 micron). Our measurements use 2 to 5 micron photometry in eclipse, Jupiter occultation, and reflected sunlight. In addition to extending the observational dataset of Io's dynamic activity, these data provide insights into the temporal and spatial distribution of outbursts on Io. Notably, all seven outbursts were detected in Io's trailing hemisphere. These include Pillan Patera and a newly discovered repeating outburst location at Acala Fluctus. We add these events to the rare category of recurring outbursts, before which Tvashtar was the only known example. We observed that another outburst at UP 254W decreased in Lp-band intensity by a factor of two in 4.5 hours. In August 2021, Io exhibited high volcanic activity when two powerful outbursts rapidly appeared, propagating East. Our findings underscore IRTF's ongoing contributions to the study of Io.

Authors:Alice S. Booth, Charles J. Law, Milou Temmink, Margot Leemker, Enrique Macias

Abstract: The composition of a forming planet is set by the material it accretes from its parent protoplanetary disk. Therefore, it is crucial to map the chemical make-up of the gas in disks to understand the chemical environment of planet formation. This paper presents molecular line observations taken with the Atacama Large Millimeter/submillimeter Array of the planet-hosting disk around the young star HD 169142. We detect N2H+, CH3OH, [CI], DCN, CS, C34S, 13CS, H2CS, H2CO, HC3N and c-C3H2 in this system for the first time. Combining these data with the recent detection of SO and previously published DCO+ data, we estimate the location of H2O and CO snowlines and investigate radial variations in the gas phase C/O ratio. We find that the HD 169142 disk has a relatively low N2H+ flux compared to the disks around Herbig stars HD 163296 and MWC 480 indicating less CO freeze-out and place the CO snowline beyond the millimetre disk at ~150 au. The detection of CH3OH from the inner disk is consistent with the H2O snowline being located at the edge of the central dust cavity at ~20 au. The radially varying CS/SO ratio across the proposed H2O snowline location is consistent with this interpretation. Additionally, the detection of CH3OH in such a warm disk adds to the growing evidence supporting the inheritance of complex ices in disks from the earlier, colder stages of star formation. Finally, we propose that the giant HD 169142 b located at 37 au is forming between the CO2 and H2O snowlines where the local elemental make of the gas is expected to have C/O=1.0.

Authors:Athul Pradeepkumar Girija

Abstract: Since the beginning of robotic interplanetary exploration nearly six decades ago, successful atmospheric entry has been accomplished at Venus, Earth, Mars, Jupiter, and Titan. More entry probe missions are planned to Venus, Titan, and Uranus in the next decade. Atmospheric entry subjects the vehicle to rapid deceleration and aerothermal loads which the vehicle must be designed for, to deliver the robotic instruments inside the atmosphere. The design of planetary probes and their mission architecture is complex, and involves various engineering constraints such as peak deceleration, heating rate, heating load, and communications which must be satisfied within the budget and schedule of cost constrained mission opportunities. Engineering design data from previous entry probe missions serve as a valuable reference for designing future missions. The present study compiles an augmented version of the blue book entry probe dataset, performs a comparative analysis of the entry conditions, and provides engineering rules of thumb for design of future missions. Using the dataset, the present study proposes a new empirical correlation which aims to more accurately predict the thermal protection system mass fraction for high heat load conditions during entry and aerocapture at Uranus and Neptune.

Authors:Swaetha Ramkumar, Neale P. Gibson, Stevanus K. Nugroho, Cathal Maguire, Mark Fortune

Abstract: The characterization of exoplanet atmospheres has proven to be successful using high-resolution spectroscopy. Phase curve observations of hot/ultra-hot Jupiters can reveal their compositions and thermal structures, thereby allowing the detection of molecules and atoms in the planetary atmosphere using the cross-correlation technique. We present pre-eclipse observations of the ultra-hot Jupiter, MASCARA-1b, observed with the recently upgraded CRIRES+ high-resolution infrared spectrograph at the VLT. We report a detection of $\rm Fe$ ($\approx$8.3$\sigma$) in the K-band and confirm previous detections of $\rm CO$ (>15$\sigma$) and $\rm H_2O$ (>10$\sigma$) in the day-side atmosphere of MASCARA-1b. Using a Bayesian inference framework, we retrieve the abundances of the detected species and constrain planetary orbital velocities, $T$-$P$ profiles, and the carbon-to-oxygen ratio ($\rm C/O$). A free retrieval results in an elevated $\rm CO$ abundance ($\log_{10}$($\chi_{\rm{{}^{12}CO}}$) = $-2.85^{+0.57}_{-0.69}$), leading to a super-solar $\rm C/O$ ratio. More realistically, allowing for vertically-varying chemistry in the atmosphere by incorporating a chemical-equilibrium model results in a $\rm C/O$ of $0.68^{+0.12}_{-0.22}$ and a metallicity of $[\rm M/H] = 0.62^{+0.28}_{-0.55}$, both consistent with solar values. Finally, we also report a slight offset of the $\rm Fe$ feature in both K$_{\rm p}$ and v$_{\rm sys}$ that could be a signature of atmospheric dynamics. Due to the 3D structure of exoplanet atmospheres and the exclusion of time/phase dependence in our 1D forward models, further follow-up observations and analysis are required to confirm or refute this result.

Authors:Jan-Vincent Harre, Alexis M. S. Smith, Teruyuki Hirano, Szilárd Csizmadia, Amaury H. M. J. Triaud, David R. Anderson

Abstract: Understanding orbital obliquities, or the misalignment angles between a star's rotation axis and the orbital axis of its planets, is crucial for unraveling the mechanisms of planetary formation and migration. In this study, we present an analysis of Rossiter-McLaughlin (RM) observations of the warm Jupiter exoplanet WASP-106 b. The high-precision radial velocity measurements were made with HARPS and HARPS-N during the transit of this planet. We aim to constrain the orientation of the planet's orbit relative to its host star's rotation axis. The RM observations are analyzed using a code which models the RM anomaly together with the Keplerian orbit given several parameters in combination with a Markov chain Monte Carlo implementation. We measure the projected stellar obliquity in the WASP-106 system for the first time and find $\lambda = (-1 \pm 11)^\circ$, supporting the theory of quiescent migration through the disk.

Authors:Adrián Rodríguez, Bruno Morgado, Nelson Callegari Jr

Abstract: Recently, it has been reported the discovery of a dense ring around the trans-Neptunian object 50000 Quaoar. The ring particles seem to be very close to the 6/1 mean motion resonance with Weywot, the only known satellite in the system. In this work we investigate the dynamical environment in the close vicinity of the 6/1 orbital resonance in the context of the restricted three body problem. We aim to analyze whether, in view of observational constraints, the ring could be effectively evolving in resonant motion with the satellite. Through the technique of dynamical maps we identify and characterize the 6/1 mean motion resonance, finding that the main location of the resonance deviates by only $29$ km from the central part of the ring. This difference lies within the 3$\sigma$ confidence level, considering the uncertainties in the observational parameters. We also show that the Weywot's eccentricity plays a significant role in the dynamical structure of the 6/1 resonance. The results show that the resonance width is smaller than the estimated ring's width. Under assumption of a ring with eccentricity smaller than 0.05, clumping of test particles appears at the position of the different resonant multiplets, considering the nominal value of Weywot's eccentricity. This is in agreement with observations, which indicate that the estimated resonance width ($\leq$ 10 km) is comparable with the narrow and dense arc of material within Quaoar's ring. Our results may be an indicative that the 6/1 resonance resonance plays a key role in confining the arc ring.

Authors:Dwaipayan Dubey, Fabian Grübel, Rosa Arenales-Lope, Karan Molaverdikhani, Barbara Ercolano, Christian Rab, Oliver Trapp

Abstract: Context: Polycyclic Aromatic Hydrocarbons, largely known as PAHs, are widespread in the universe and have been identified in a vast array of astronomical observations from the interstellar medium to protoplanetary discs. They are likely to be associated with the chemical history of the universe and the emergence of life on Earth. However, their abundance on exoplanets remains unknown. Aims: We aim to investigate the feasibility of PAH formation in the thermalized atmospheres of irradiated and non-irradiated hot Jupiters around Sun-like stars. Methods: To this aim, we introduced PAHs in the 1-D self-consistent forward modeling code petitCODE. We simulated a large number of planet atmospheres with different parameters (e.g. carbon to oxygen ratio, metallicity, and effective planetary temperature) to study PAH formation. By coupling the thermochemical equilibrium solution from petitCODE with the 1-D radiative transfer code, petitRADTRANS, we calculated the synthetic transmission and emission spectra for irradiated and non-irradiated planets, respectively, and explored the role of PAHs on planet spectra. Results: Our models show strong correlations between PAH abundance and the aforementioned parameters. In thermochemical equilibrium scenarios, an optimal temperature, elevated carbon to oxygen ratio, and increased metallicity values are conducive to the formation of PAHs, with the carbon to oxygen ratio having the largest effect.

Authors:Byeong-Cheol Lee, Gwanghui Jeong, Jae-Rim Koo, Beomdu Lim, Myeong-Gu Park, Tae-Yang Bang, Yeon-Ho Choi, Hyeong-Ill Oh, Inwoo Han

Abstract: This paper is written as a follow-up observations to reinterpret the radial velocity (RV) of HD 36384, where the existence of planetary systems is known to be ambiguous. In giants, it is, in general, difficult to distinguish the signals of planetary companions from those of stellar activities. Thus, known exoplanetary giant hosts are relatively rare. We, for many years, have obtained RV data in evolved stars using the high-resolution, fiber-fed Bohyunsan Observatory Echelle Spectrograph (BOES) at the Bohyunsan Optical Astronomy Observatory (BOAO). Here, we report the results of RV variations in the M giant HD 36384. We have found two significant periods of 586d and 490d. Considering the orbital stability, it is impossible to have two planets at so close orbits. To determine the nature of the RV variability variations, we analyze the HIPPARCOS photometric data, some indicators of stellar activities, and line profiles. A significant period of 580d was revealed in the HIPPARCOS photometry. H{\alpha} EW variations also show a meaningful period of 582d. Thus, the period of 586d may be closely related to the rotational modulations and/or stellar pulsations. On the other hand, the other significant period of 490d is interpreted as the result of the orbiting companion. Our orbital fit suggests that the companion was a planetary mass of 6.6 MJ and is located at 1.3 AU from the host.

Authors:Imre Kisvárdai, Bernadett D. Pál, Ákos Kereszturi

Abstract: The interior of Enceladus, a medium sized icy moon of Saturn hosts hydrothermal activity and exhibits tidal heating and related geyser-like activity. There are major disagreements in the existing literature on the porosity of the interior, due to the different theoretical assumptions on which porosity related calculations were based. We present an application of experimental equations - derived for Earth - for icy planetary objects and Enceladus in particular. We chose a set of boundary values for our initial parameters from measured porosity values of chondrite samples as references, and calculated the porosity related values of Enceladus using various approaches. We present a comprehensive investigation of the effects of using these different porosity calculation methods on icy moons. With our most realistic approach we also calculated the same values for Earth and Mars for comparison. Our result for Enceladus is a minimum porosity of about 5\% at the centre of the body. For the total pore volume we estimated $1.51*10^7 km^3$ for Enceladus, $2.11*10^8 km^3$ for Earth and $1.62*10^8 km^3$ for Mars. Using the same method, we estimated the total pore surface area. From this we derived that the pore surface under a given $1 km^2$ area of the surface on Enceladus is about $1.37*10^9 km^2$, while for Earth this value is only $5.07*10^7 km^2$.

Authors:A. García Muñoz

Abstract: Context. The long-term evolution of an atmosphere and the remote detectability of its chemical constituents are susceptible to how the atmospheric gas responds to stellar irradiation. The response remains poorly characterized for water and its dissociation products, however, this knowledge is relevant to our understanding of hypothetical water-rich exoplanets. Aims: Our work investigates the effect of photoelectrons, namely, the non-thermal electrons produced by photoionizing stellar radiation on the heating and ionization of extended atmospheres dominated by the dissociation products of water. Methods: We used a Monte Carlo model and up-to-date collision cross sections to simulate the slowing down of photoelectrons in O-H mixtures for a range of fractional ionizations and photoelectron energies. Results: We find that that the fraction of energy of a photoelectron that goes into heating is similar in a pure H gas and in O-H mixtures, except for very low fractional ionizations, whereby the O atom remains an efficient sink of energy. The O-H mixtures will go on to produce more electrons because the O atom is particularly susceptible to ionization. We quantified all that information and present it in a way that can be easily incorporated into photochemical-hydrodynamical models. Conclusions: Neglecting the role of photoelectrons in models of water-rich atmospheres will result in overestimations of the atmospheric heating and, foreseeably, the mass-loss rates as well. It will also underestimate the rate at which the atmospheric gas becomes ionized, which may have implications for the detection of extended atmospheres with Lyman-{\alpha} transmission spectroscopy. Our simulations for the small exoplanets {\pi} Men c and TRAPPIST-1 b reveal that they respond very differently to irradiation from their host stars, with water remaining in molecular form at lower pressures in the latter case.

Authors:Kevin Heng

Abstract: The enigmatic nature of 55 Cancri e has defied theoretical explanation. Any explanation needs to account for the observed variability of its secondary eclipse depth, which is at times consistent with zero in the visible/optical range of wavelengths -- a phenomenon that does not occur with its also variable infrared eclipses. Yet, despite this variability its transit depth remains somewhat constant in time and is inconsistent with opaque material filling its Hill sphere. The current study explores the possibility of a thin, transient, secondary atmosphere on 55 Cancri e that is sourced by geochemical outgassing. Its transient nature derives from the inability of outgassing to be balanced by atmospheric escape. As the outgassed atmosphere escapes and is replenished, it rapidly adjusts to radiative equilibrium and the temperature fluctuations cause the infrared eclipse depths to vary. Atmospheres of pure carbon dioxide or carbon monoxide produce sufficient Rayleigh scattering to explain the observed optical/visible eclipse depths, which vanish in the absence of an atmosphere and the presence of a dark rocky surface. Atmospheres of pure methane are ruled out because they produce insufficient Rayleigh scattering. Upcoming observations by the James Webb Space Telescope will potentially allow the atmospheric temperature and surface pressure, as well as the surface temperature, to be measured.

Authors:P. Hatalova, R. Brasser, E. Mamonova, S. C. Werner

Abstract: How multiple close-in super-Earths form around stars with masses lower than that of the Sun is still an open issue. Several recent modeling studies have focused on planet formation around M-dwarf stars, but so far no studies have focused specifically on K dwarfs, which are of particular interest in the search for extraterrestrial life. We aim to reproduce the currently known population of close-in super-Earths observed around K-dwarf stars and their system characteristics. We performed 48 high-resolution N-body simulations of planet formation via planetesimal accretion using the existing GENGA software running on GPUs. In the simulations we varied the initial disk mass and the solid and gas surface density profiles. Each simulation began with 12000 bodies with radii of between 200 and 2000 km around two different stars, with masses of 0.6 and 0.8 $M_{\odot}$. Most simulations ran for 20 Myr, with several simulations extended to 40 or 100 Myr. The mass distributions for the planets with masses between 2 and 12 $M_\oplus$ show a strong preference for planets with masses $M_p<6$ $M_\oplus$ and a lesser preference for planets with larger masses, whereas the mass distribution for the observed sample increases almost linearly. However, we managed to reproduce the main characteristics and architectures of the known planetary systems and produce mostly long-term angular-momentum-deficit-stable, nonresonant systems, but we require an initial disk mass of 15 $M_\oplus$ or higher and a gas surface density value at 1 AU of 1500 g cm$^{-2}$ or higher. Our simulations also produce many low-mass planets with $M<2$ $M_\oplus$, which are not yet found in the observed population, probably due to the observational biases. The final systems contain only a small number of planets, which could possibly accrete substantial amounts of gas, and these formed after the gas had mostly dissipated.

Authors:Chima D. McGruder, Mercedes López-Morales, James Kirk, Erin May, Benjamin V. Rackham, Munazza K. Alam, Natalie H. Allen, John D. Monnier, Kelly Meyer, Tyler Gardner, Kevin Ortiz Ceballos, Eva-Maria Ahrer, Peter J. Wheatley, George W. King, Andrés Jordán, David J. Osip, Néstor Espinoza

Abstract: We present new optical transmission spectra for two hot Jupiters: WASP-25b (M = 0.56~M$_J$; R = 1.23 R$_J$; P =~3.76 days) and WASP-124b (M = 0.58~M$_J$; R = 1.34 R$_J$; P = 3.37 days), with wavelength coverages of 4200 - 9100\AA\ and 4570 - 9940\AA, respectively. These spectra are from the ESO Faint Object Spectrograph and Camera (v.2) mounted on the New Technology Telescope (NTT) and Inamori-Magellan Areal Camera & Spectrograph on Magellan Baade. No strong spectral features were found in either spectra, with the data probing 4 and 6 scale heights, respectively. \texttt{Exoretrievals} and \texttt{PLATON} retrievals favor stellar activity for WASP-25b, while the data for WASP-124b did not favor one model over another. For both planets the retrievals found a wide range in the depths where the atmosphere could be optically thick ($\sim0.4\mu$ - 0.2 bars for WASP-25b and 1.6 $\mu$ -- 32 bars for WASP-124b) and recovered a temperature that is consistent with the planets' equilibrium temperatures, but with wide uncertainties (up to $\pm$430$^\circ$K). For WASP-25b, the models also favor stellar spots that are $\sim$500-3000$^\circ$K cooler than the surrounding photosphere. The fairly weak constraints on parameters are owing to the relatively low precision of the data, with an average precision of 840 and 1240 ppm per bin for WASP-25b and WASP-124b, respectively. However, some contribution might still be due to an inherent absence of absorption or scattering in the planets' upper atmospheres, possibly because of aerosols. We attempt to fit the strength of the sodium signals to the aerosol-metallicity trend proposed by McGruder et al. 2023, and find WASP-25b and WASP-124b are consistent with the prediction, though their uncertainties are too large to confidently confirm the trend.

Authors:Huan-Yu Teng, Bun'ei Sato, Masayuki Kuzuhara, Takuya Takarada, Masashi Omiya, Hiroki Harakawa, Hideyuki Izumiura, Eiji Kambe, Mesut Yilmaz, Ilfan Bikmaev, Selim O. Selam, Timothy D. Brandt, Guang-Yao Xiao, Michitoshi Yoshida, Yoichi Itoh, Hiroyasu Ando, Eiichiro Kokubo, Shigeru Ida

Abstract: In this study, we revisit 32 planetary systems around evolved stars observed within the framework of the Okayama Planet Search Program and its collaborative framework of the EAPS-Net to search for additional companions and investigate the properties of stars and giant planets in multiple-planet systems. With our latest radial velocities obtained from Okayama Astrophysical Observatory (OAO), we confirm an additional giant planet in the wide orbit of 75 Cet system ($P_{\rm{c}} = 2051.62_{-40.47}^{+45.98}\ \rm{d}$, $M_{\rm{c}}\sin i=0.912_{-0.090}^{+0.088}\ M_{\rm{J}}$, and $a_{\rm{c}}=3.929_{-0.058}^{+0.052}\ \rm{au}$), along with five stars exhibiting long-term radial velocity accelerations, which indicates massive companions in the wide orbits. We have also found that the radial velocity variations of several planet-harboring stars may indicate additional planet candidates, stellar activities, or other understudied sources. These stars include $\epsilon$ Tau, 11 Com, 24 Boo, 41 Lyn, 14 And, HD 32518, and $\omega$ Ser. We further constrain the orbital configuration of the HD 5608, HD 14067, HD 120084, and HD 175679 systems by combining radial velocities with astrometry, as their host central stars exhibit significant astrometric accelerations. For other systems, we simply refine their orbital parameters. Moreover, our study indicates that the OPSP planet-harboring stars are more metal-poor compared to the currently known planet-harboring stars, and this is likely due to the $B-V$ color upper limit at 1.0 for star selection in the beginning of the survey. Finally, by investigating the less-massive giant planets ($< 5 M_{\rm{J}}$) around currently known planet-harboring evolved stars, we have found that metallicity positively correlates with the multiplicity and total planet mass of the system, which can be evidence for the core-accretion planet formation model.

Authors:Josef Hanuš, David Vokrouhlický, David Nesvorný, Josef Ďurech, Robert Stephens, Vladimir Benishek, Julian Oey, Petr Pokorný

Abstract: The leading theory for the origin of Jupiter Trojans (JTs) assumes that JTs were captured to their orbits near the Lagrangian points of Jupiter during the early reconfiguration of the giant planets. The natural source region for the majority of JTs would then be the population of planetesimals born in a massive trans-Neptunian disk. If true, JTs represent the most accessible stable population of small Solar System bodies that formed in the outer regions of the Solar System. For this work, we compiled photometric datasets for about 1000 JTs and applied the convex inversion technique in order to assess their shapes and spin states. We obtained full solutions for $79$ JTs, and partial solutions for an additional $31$ JTs. We found that the observed distribution of the pole obliquities of JTs is broadly consistent with expectations from the streaming instability, which is the leading mechanism for the formation of planetesimals in the trans-Neptunian disk. The observed JTs' pole distribution has a slightly smaller prograde vs. retrograde asymmetry (excess of obliquities $>130^\circ$) than what is expected from the existing streaming instability simulations. However, this discrepancy can be plausibly reconciled by the effects of the post-formation collisional activity. Our numerical simulations of the post-capture spin evolution indicate that the JTs' pole distribution is not significantly affected by dynamical processes such as the eccentricity excitation in resonances, close encounters with planets, or the effects of nongravitational forces. However, a few JTs exhibit large latitude variations of the rotation pole and may even temporarily transition between prograde- and retrograde-rotating categories.

Authors:F. Philipot, A. -M. Lagrange, F. Kiefer, P. Rubini, P. Delorme, A. Chomez

Abstract: Context. Although more than one thousand sub-stellar companions have already been detected with the radial velocity (RV) method, many new companions remain to be detected in the public RV archives. Aims. We wish to use the archival data obtained with the ESO/HARPS spectrograph to search for sub-stellar companions. Methods. We use the astronomic acceleration measurements of stars obtained with the Hipparcos and Gaia satellites to identify anomalies that could be explained by the presence of a companion. Once hints for a companion are found, we combine the RV data with absolute astrometry and, when available, relative astrometry data, using a Markov Chain Monte Carlo (MCMC) algorithm to determine the orbital parameters and mass of the companion. Results. We find and characterize three new brown dwarfs (GJ660.1 C, HD73256 B, and HD165131 B) and six new planets (HD75302 b, HD108202 b, HD135625 b, HD185283 b, HIP10337 b, and HIP54597 b) with separations between 1 and 6 au and masses between 0.6 and 100 MJup. We also constrain the orbital inclination of ten known sub-stellar companions and determine their true mass. Finally, we identify twelve new stellar companions. This shows that the analysis of proper motion anomalies allows for optimizing the RV search for sub-stellar companions and their characterization.

Authors:Marko Gacesa

Abstract: We report elastic and inelastic cross sections for fast superthermal $^{12}$C($^3P$) and $^{13}$C($^3P$) atoms scattering on $^{12}$CO$_2$. The cross sections were computed using quantum-mechanical rotationally close-coupling formalism with the electronic interaction described by a newly constructed potential energy surface correlating to the lowest energy asymptote of the complex. State-to-state cross sections, differential cross sections, and derived transport properties of interest for energy relaxation are also reported. The computed elastic cross sections are strongly anisotropic, show significant energy dependence, and differ by up to 2% between the two isotopes of carbon.

Authors:C. K. Louis, P. Louarn, B. Collet, N. Clément, S. Al Saati, J. R. Szalay, V. Hue, L. Lamy, S. Kotsiaros, W. S. Kurth, C. M. Jackman, Y. Wang, M. Blanc, F. Allegrini, J. E. P. Connerney, D. Gershman

Abstract: At Jupiter, part of the auroral radio emissions are induced by the Galilean moons Io, Europa and Ganymede. Until now, except for Ganymede, they have been only remotely detected, using ground-based radio-telescopes or electric antennas aboard spacecraft. The polar trajectory of the Juno orbiter allows the spacecraft to cross the range of magnetic flux tubes which sustain the various Jupiter-satellite interactions, and in turn to sample in situ the associated radio emission regions. In this study, we focus on the detection and the characterization of radio sources associated with Io, Europa and Ganymede. Using electric wave measurements or radio observations (Juno/Waves), in situ electron measurements (Juno/JADE-E), and magnetic field measurements (Juno/MAG) we demonstrate that the Cyclotron Maser Instability (CMI) driven by a loss-cone electron distribution function is responsible for the encountered radio sources. We confirmed that radio emissions are associated with Main (MAW) or Reflected Alfv\'en Wing (RAW), but also show that for Europa and Ganymede, induced radio emissions are associated with Transhemispheric Electron Beam (TEB). For each traversed radio source, we determine the latitudinal extension, the CMI-resonant electron energy, and the bandwidth of the emission. We show that the presence of Alfv\'en perturbations and downward field aligned currents are necessary for the radio emissions to be amplified.

Authors:S. Stasevic, J. Milli, J. Mazoyer, A. -M. Lagrange, M. Bonnefoy, V. Faramaz-Gorka, F. Ménard, A. Boccaletti, E. Choquet, L. Shuai, J. Olofsson, A. Chomez, B. Ren, P. Rubini, C. Desgrange, R. Gratton, G. Chauvin, A. Vigan, E. Matthews

Abstract: An edge-on debris disk was detected in 2015 around the young, nearby A0V star HD 110058. The disk showed features resembling those seen in the disk of beta Pictoris that could indicate the presence of a perturbing planetary-mass companion in the system. We investigated new and archival scattered light images of the disk in order to characterise its morphology and spectrum. In particular, we analysed the disk's warp to constrain the properties of possible planetary perturbers. Our work uses data from two VLT/SPHERE observations and archival data from HST/STIS. We measured the morphology of the disk by analysing vertical profiles along the length of the disk to extract the centroid spine position and vertical height. We extracted the surface brightness and reflectance spectrum of the disk. We detect the disk between 20 au (with SPHERE) and 150 au (with STIS), at a position angle of 159.6$^\circ\pm$0.6$^\circ$. Analysis of the spine shows an asymmetry between the two sides of the disk, with a 3.4$^\circ\pm$0.9$^\circ$ warp between ~20 au and 60 au. The disk is marginally vertically resolved in scattered light, with a vertical aspect ratio of 9.3$\pm$0.7% at 45 au. The extracted reflectance spectrum is featureless, flat between 0.95 micron and 1.1 micron, and red from 1.1 micron to 1.65 micron. The outer parts of the disk are also asymmetric with a tilt between the two sides compatible with a disk made of forward-scattering particles and seen not perfectly edge-on, suggesting an inclination of <84$^\circ$. The presence of an undetected planetary-mass companion on an inclined orbit with respect to the disk could explain the warp. The misalignment of the inner parts of the disk with respect to the outer disk suggests a warp that has not yet propagated to the outer parts of the disk, favouring the scenario of an inner perturber as the origin of the warp.

Authors:Marie-Luise Steinmeyer, Peter Woitke, Anders Johansen

Abstract: Protoplanets growing within the protoplanetary disk by pebble accretion acquire hydrostatic gas envelopes. Due to accretion heating, the temperature in these envelopes can become high enough to sublimate refractory minerals which are the major components of the accreted pebbles. Here we study the sublimation of different mineral species and determine whether sublimation plays a role during the growth by pebble accretion. For each snapshot in the growth process, we calculate the envelope structure and sublimation temperature of a set of mineral species representing different levels of volatility. Sublimation lines are determined using and equilibrium scheme for the chemical reactions responsible for destruction and formation of the relevant minerals. We find that the envelope of the growing planet reaches temperatures high enough to sublimate all considered mineral species when the mass is larger than 0.4 Earth masses. The sublimation lines are located within the gravitionally bound envelope of the planet. We make a detailed analysis of the sublimation of FeS at around 720 K, beyond which the mineral is attacked by H2 to form gaseous H2S and solid Fe. We calculate the sulfur concentration in the planet under the assumption that all sulfur released as H2S is lost from the planet by diffusion back to the protoplanetary disk. Our calculated values are in good agreement with the slightly depleted sulfur abundance of Mars, while the model overpredicts the extensive sulfur depletion of Earth by a factor of approximately 2. We show that a collision with a sulfur-rich body akin to Mars in the moon-forming impact lifts the Earth's sulfur abundance to approximately 10% of the solar value for all impactor masses above 0.05 Earth masses.

Authors:M. Stalport, M. Cretignier, S. Udry, A. Anna John, T. G. Wilson, J. -B. Delisle, A. S. Bonomo, L. A. Buchhave, D. Charbonneau, S. Dalal, M. Damasso, L. Di Fabrizio, X. Dumusque, A. Fiorenzano, A. Harutyunyan, R. D. Haywood, D. W. Latham, M. López-Morales, V. Lorenzi, C. Lovis, L. Malavolta, E. Molinari, A. Mortier, M. Pedani, F. Pepe, M. Pinamonti, E. Poretti, K. Rice, A. Sozzetti

Abstract: The Rocky Planet Search (RPS) program is dedicated to a blind radial velocity (RV) search of planets around bright stars in the Northern hemisphere, using the high-resolution echelle spectrograph HARPS-N installed on the Telescopio Nazionale Galileo (TNG). The goal of this work is to revise and update the properties of three planetary systems by analysing the HARPS-N data with state-of-the-art stellar activity mitigation tools. The stars considered are HD 99492 (83Leo B), HD 147379 (Gl617 A) and HD 190007. We employ a systematic process of data modelling, that we selected from the comparison of different approaches. We use YARARA to remove instrumental systematics from the RV, and then use SPLEAF to further mitigate the stellar noise with a multidimensional correlated noise model. We also search for transit features in the Transiting Exoplanets Survey Satellite (TESS) data of these stars. We report on the discovery of a new planet around HD 99492, namely HD 99492 c, with an orbital period of 95.2 days and a minimum mass of msin i = 17.9 M_Earth, and refine the parameters of HD 99492 b. We also update and refine the Keplerian solutions for the planets around HD 147379 and HD 190007, but do not detect additional planetary signals. We discard the transiting geometry for the planets, but stress that TESS did not exhaustively cover all the orbital phases. The addition of the HARPS-N data, and the use of advanced data analysis tools, has allowed us to present a more precise view of these three planetary systems. It demonstrates once again the importance of long observational efforts such as the RPS program. Added to the RV exoplanet sample, these planets populate two apparently distinct populations revealed by a bimodality in the planets minimum mass distribution. The separation is located between 30 and 50 M_Earth.

Authors:M. Pettine, S. Imbeah, J. Rathbun, A. Hayes, R. Lopes-Gautier, A. Mura, F. Tosi, F. Zambon, S. Bertolino

Abstract: The Jovian Infrared Auroral Mapper (JIRAM) instrument aboard Juno has allowed clear, high-resolution imaging of Io's polar volcanoes. We have used data from JIRAM's M-band (4.78 micron) imager from eleven Juno orbits to construct a global map of volcanic flux. This map provides insight into the spatial distribution of volcanoes and the ways in which high- and low-latitude volcanoes differ. Using spherical harmonic analysis, we have quantitatively compared our volcanic flux map to the surface heat flow distribution expected by modeling data of Io's tidal heat deposition (de Kleer et al. 2019). Systems of bright volcanoes were confirmed at high latitudes. Our study finds that both poles are more active than previous studies have suggested, although the south pole was viewed too infrequently to establish reliable long-term trends. While none of the tidal heat flow models match well, the asthenospheric heating model agrees best with the observed volcanic flux.

Authors:A. G. Sreejith, Kevin France, Luca Fossati, Tommi T. Koskinen, Arika Egan, P. Wilson Cauley, Patricio. E. Cubillos, S. Ambily, Chenliang Huang, 5 Panayotis Lavvas, Brian T. Fleming, Jean-Michel Desert, Nicholas Nell, Pascal Petit, Aline Vidotto

Abstract: Ultraviolet observations of Ultra-hot Jupiters (UHJs), exoplanets with temperatures over 2000\,K, provide us with an opportunity to investigate if and how atmospheric escape shapes their upper atmosphere. Near-ultraviolet transit spectroscopy offers a unique tool to study this process owing to the presence of strong metal lines and a bright photospheric continuum as the light source against which the absorbing gas is observed. WASP-189b is one of the hottest planets discovered to date, with a day-side temperature of about 3400\,K orbiting a bright A-type star. We present the first near-ultraviolet observations of WASP-189b, acquired with the Colorado Ultraviolet Transit Experiment ($CUTE$). $CUTE$ is a 6U NASA-funded ultraviolet spectroscopy mission, dedicated to monitoring short-period transiting planets. WASP-189b was one of the $CUTE$ early science targets and was observed during three consecutive transits in March 2022. We present an analysis of the $CUTE$ observations and results demonstrating near-ultraviolet (2500--3300~\AA) broadband transit depth ($1.08^{+0.08}_{-0.08}\%$) of about twice the visual transit depth indicating that the planet has an extended, hot upper atmosphere with a temperature of about 15000\,K and a moderate mass loss rate of about \SI{4e8}{\kg\per\second}. We observe absorption by Mg{\sc ii} lines ($R_p/R_s$ of $0.212^{+0.038}_{-0.061}$) beyond the Roche lobe at $>$4$\sigma$ significance in the transmission spectrum at a resolution of 10~\AA, while at lower resolution (100~\AA), we observe a quasi-continuous absorption signal consistent with a "forest" of low-ionization metal absorption dominated by Fe{\sc ii}. The results suggest an upper atmospheric temperature ($\sim15000$\,K), higher than that predicted by current state-of-the-art hydrodynamic models.

Authors:Tenri Jinno, Takayuki R. Saitoh, Yota Ishigaki, Junichiro Makino

Abstract: In the conventional theory of planet formation, it is assumed that protoplanetary disks are axisymmetric and have a smooth radial profile. However, recent radio observations of protoplanetary disks have revealed that many of them have complex radial structures. In this study, we perform a series of $N$-body simulations to investigate how planets are formed in protoplanetary disks with radial structures. For this purpose, we consider the effect of continuous pebble accretion onto the discontinuity boundary within the terrestrial planet-forming region ($\sim0.6$ AU). We found that protoplanets grow efficiently at the discontinuity boundary, reaching the Earth mass within $\sim10^4$ years. We confirmed that giant collisions of protoplanets occur universally in our model. Moreover, we found that multiple planet-sized bodies form at regular intervals in the vicinity of the discontinuity boundary. These results indicate the possibility of the formation of solar system-like planetary systems in radially structured protoplanetary disks.

Authors:Sean M. Wahl, Daniel Thorngren, Tiger Lu, Burkhard Militzer

Abstract: We study the response of hot Jupiters to a static tidal perturbation using the Concentric MacLaurin Spheroid (CMS) method. For strongly irradiated planets, we first performed radiative transfer calculations to relate the planet's equilibrium temperature, T_eq, to its interior entropy. We then determined the gravity harmonics, shape, moment of inertia, and the static Love numbers for a range of two-layer interior models that assume a rocky core plus a homogeneous and isentropic envelope composed of hydrogen, helium, and heavier elements. We identify general trends and then study HAT-P-13b, the WASP planets 4b, 12b, 18b, 103b, and 121b, as well as Kepler-75b and CoRot-3b. We compute the Love numbers, k_nm, and transit radius correction, Delta R, which we compare with predictions in the literature. We find that the Love number, k_22, of tidally locked giant planets cannot exceed the value 0.6, and that the high T_eq consistent with strongly irradiated hot Jupiters tend %lead to further lower k_22. While most tidally locked planets are well described by a linear-regime response of k_22 = 3 J_2/q_0 (where q_0 is the rotation parameter of the gravitational potential), for extreme cases such as WASP-12b, WASP-103b and WASP-121b, nonlinear effects can account for over 10% of the predicted k_22. k_22 values larger than 0.6, as they have been reported for planets WASP-4b and HAT-P13B, cannot result from a static tidal response without extremely rapid rotation, and thus are inconsistent with their expected tidally-locked state.

Authors:F. Cruz Aguirre, K. France, N. Nell, N. Kruczek, B. Fleming, P. C. Hinton, S. Ulrich, P. R. Behr

Abstract: Far ultraviolet (FUV) emission lines from dwarf stars are important driving sources of photochemistry in planetary atmospheres. Properly interpreting spectral features of planetary atmospheres critically depends on the emission of its host star. While the spectral energy distributions (SEDs) of K- and M-type stars have been extensively characterized by previous observational programs, the full X-ray to infrared SED of F-type stars has not been assembled to support atmospheric modeling. On the second flight of the Suborbital Imaging Spectrograph for Transition-region Irradiance from Nearby Exoplanet host stars (SISTINE-2) rocket-borne spectrograph, we successfully captured the FUV spectrum of Procyon A (F5 IV-V) and made the first simultaneous observation of several emission features across the FUV bandpass (1010 - 1270 and 1300 - 1565 \r{A}) of any cool star. We combine flight data with stellar models and archival observations to develop the first SED of a mid-F star. We model the response of a modern Earth-like exoplanet's upper atmosphere to the heightened X-ray and extreme ultraviolet radiation within the habitable zone of Procyon A. These models indicate that this planet would not experience significant atmospheric escape. We simulate observations of the Ly$\alpha$ transit signal of this exoplanet with the Hubble Space Telescope (HST) and the Habitable Worlds Observatory (HWO). While marginally detectable with HST, we find that H I Ly$\alpha$ transits of potentially habitable exoplanets orbiting high radial velocity F-type stars could be observed with HWO for targets up to 150 pc away.

Authors:Burkhard Militzer, William B. Hubbard

Abstract: We study the relationship of zonal gravity coefficients, J_2n, zonal winds, and axial moment of inertia (MoI) by constructing models for the interiors of giant planets. We employ the nonperturbative concentric Maclaurin spheroid (CMS) method to construct both physical (realistic equation of state and barotropes) and abstract (small number of constant-density spheroids) interior models. We find that accurate gravity measurements of Jupiter's and Saturn's J_2, J_4, and J_6 by Juno and Cassini spacecrafts do not uniquely determine the MoI of either planet but do constrain it to better than 1%. Zonal winds (or differential rotation, DR) then emerge as the leading source of uncertainty. For Saturn, they are predicted to decrease the MoI by 0.4% because they reach a depth of ~9000 km while on Jupiter, they appear to reach only ~3000 km. We thus predict DR to affect Jupiter's MoI by only 0.01%, too small by one order of magnitude to be detectable by the Juno spacecraft. We find winds primarily affect the MoI indirectly via the gravity harmonic J_6 while direct contributions are much smaller because the effects of pro- and retrograde winds cancel. DR contributes +6% and -0.8% to Saturn's and Jupiter's J_6 value, respectively. This changes the J_6 contribution that comes from the uniformly rotating bulk of the planet that correlates most strongly with the predicted MoI. With our physical models, we predict Jupiter's MoI to be 0.26393+-0.00001. For Saturn, we predict 0.2181+-0.0002, assuming a rotation period of 10:33:34 h that matches the observed polar radius.

Authors:Burkhard Militzer

Abstract: We construct models for Jupiter's interior that match the gravity data obtained by the Juno and Galileo spacecrafts. To generate ensembles of models, we introduce a novel quadratic Monte Carlo technique that is more efficient in confining fitness landscapes than affine invariant method that relies on linear stretch moves. We compare how long it takes the ensembles of walkers in both methods to travel to the most relevant parameter region. Once there, we compare the autocorrelation time and error bars of the two methods. For a ring potential and the 2d Rosenbrock function, we find that our quadratic Monte Carlo technique is significantly more efficient. Furthermore we modified the walk moves by adding a scaling factor. We provide the source code and examples so that this method can be applied elsewhere. Here we employ our method to generate five-layer models for Jupiter's interior that include winds and a prominent dilute core, which allows us to match the planet's even and odd gravity harmonics. We compare predictions from the different model ensembles and analyze how much an increase of the temperature at 1 bar and ad hoc change to the equation of state affects the inferred amount of heavy elements in atmosphere and in the planet overall.

Authors:Pin-Gao Gu, Howard Chen

Abstract: We investigate the evolution of deuterium to hydrogen mass ratio (D/H) driven by EUV photoevaporation of hydrogen-rich atmospheres of close-in sub-Neptunes around solar-type stars. For the first time, the diffusion-limited approach in conjunction with energy-limited photoevaporation is considered in evaluating deuterium escape from evolving exoplanet H/He envelopes. We find that the planets with smaller initial gas envelopes and thus smaller sizes can lead to weaker atmospheric escape, which facilitates hydrogen-deuterium fractionation. Specifically, in our grid of simulations with a low envelope mass fraction less than 0.005, a low-mass sub-Neptune (4-$5M_\oplus$) at about 0.25-0.4 au or a high-mass sub-Neptune (10-$15M_\oplus$) at about 0.1-0.25 au can increase the D/H values by greater than 20% over 7.5 Gyrs. Akin to the helium-enhanced envelopes of sub-Neptunes due to photoevaporating escape, the planets along the upper boundary of the radius valley are the best targets to detect high D/H ratios. The ratio can rise by a factor of $\lesssim$ 1.65 within 7.5 Gyrs in our grid of evolutionary calculations. D/H is expected to be higher in thinner envelopes so long as the planets do not become bare rocky cores.

Authors:N. W. Borsato, H. J. Hoeijmakers, D. Cont, D. Kitzmann, J. Ehrhardt, C. Gössl, C. Ries, B. Prinoth, K. Molaverdikhani, B. Ercolano, H. Kellerman, Kevin Heng

Abstract: When observing transmission spectra produced by atmospheres of ultra-hot Jupiters, large telescopes are typically the instrument of choice due to the very weak signal of the planet's atmosphere. This study aims to alleviate the desire for large telescopes by illustrating that the same science is possible with smaller telescope classes. We use the cross-correlation technique to showcase the potential of the high-resolution spectrograph FOCES at Wendelstein Observatory and demonstrate its potential to resolve the atmosphere of the ultra-hot Jupiter, KELT-9 b. A performance comparison is conducted between FOCES and HARPS-N spectrographs, considering both single transit and combined observations over three nights. With FOCES, we have detected seven species in KELT-9 b's atmosphere: Ti II, Fe I, Fe II, Na I, Mg I, Na II, Cr II, Sc II. Although HARPS-N surpasses FOCES in performance, our results reveal that smaller telescope classes are capable of resolving ultra-hot Jupiter atmospheres. This broadens the scope of potential studies, allowing for investigations into phenomena like temporal variations in atmospheric signals and the atmospheric loss characteristics of these close-in planets.

Authors:Sandeep Sahijpal

Abstract: N-body numerical simulations code for the orbital motion of asteroids/planetesimals within the asteroid belt under the gravitational influence of the sun and the accreting planets has been developed. The aim is to make qualitative, and to an extent a semi-quantitative argument, regarding the possible extent of radial mixing and homogenization of planetesimal reservoirs of the two observed distinct spectral types , viz., the S-type and C-type, across the heliocentric distances due to their dynamical orbital evolution, thereby, eventually leading to the possible accretion of asteroids having chemically diverse constituents. The spectral S-type and C-type asteroids are broadly considered as the parent bodies of the two observed major meteoritic dichotomy classes, namely, the non-carbonaceous (NC) and carbonaceous (CC) meteorites, respectively. The present analysis is performed to understand the evolution of the observed dichotomy and its implications due to the nebula and early planetary processes during the initial 10 Myrs (Million years). The homogenization across the two classes is studied in context to the accretion timescales of the planetesimals with respect to the half-life of the potent planetary heat source, 26Al. The accretion over a timescale of ~1.5 Myr. possibly resulted in the planetary-scale differentiation of planetesimals to produce CC and NC achondrites and iron meteorite parent bodies, whereas, the prolonged accretion over a timescale of 2-5 Myrs. resulted in the formation of CC and NC chondrites. Our simulation results indicate a significant role of the initial eccentricities and the masses of the accreting giant planets, specifically, Jupiter and Saturn, in triggering the eccentricity churning of the planetesimals across the radial distances......

Authors:Yash Gondhalekar, Eric D. Feigelson, Gabriel A. Caceres, Marco Montalto, Snehanshu Saha

Abstract: We conduct a methodological study for statistically comparing the sensitivities of two periodograms for weak signal planet detection in transit surveys: the widely used Box-Least Squares (BLS) algorithm following light curve detrending and the Transit Comb Filter (TCF) algorithm following autoregressive ARIMA modeling. Small depth transits are injected into light curves with different simulated noise characteristics. Two measures of spectral peak significance are examined: the periodogram signal-to-noise ratio (SNR) and a False Alarm Probability (FAP) based on the generalized extreme value distribution. The relative performance of the BLS and TCF algorithms for small planet detection is examined for a range of light curve characteristics, including orbital period, transit duration, depth, number of transits, and type of noise. The TCF periodogram applied to ARIMA fit residuals with the SNR detection metric is preferred when short-memory autocorrelation is present in the detrended light curve and even when the light curve noise had white Gaussian noise. BLS is more sensitive to small planets only under limited circumstances with the FAP metric. BLS periodogram characteristics are inferior when autocorrelated noise is present. Application of these methods to TESS light curves with small exoplanets confirms our simulation results. The study ends with a decision tree that advises transit survey scientists on procedures to detect small planets most efficiently. The use of ARIMA detrending and TCF periodograms can significantly improve the sensitivity of any transit survey with regularly spaced cadence.

Authors:K. I. Dale, D. C. Rubie, M. Nakajima, S. Jacobson, G. Nathan, G. J. Golabek, S. Cambioni, A. Morbidelli

Abstract: We improved the algorithm presented in Rubie et al. (2015) to model the chemical evolution of Earth driven by iron/silicate differentiation during the planet's accretion. The pressure at which the equilibration occurs during a giant impact is no longer a free parameter but is determined by the smooth particle hydrodynamic (SPH) simulations of Nakajima et al. (2021). Moreover, impacting planetesimals are now assumed to be too small to cause melting and differentiation and thus their materials are stored in the crystalline upper mantle of the growing planet until a hydrostatically relaxed global magma ocean forms in the aftermath of a giant impact, whose depth is also estimated from Nakajima et al. (2021). With these changes, not all dynamical simulations lead to a satisfactory reproduction of the chemical composition of the bulk silicate Earth (BSE). Thus, the latter becomes diagnostic of the success of dynamical models. In the successful cases also the BSE abundances of W and Mo can be reproduced, that were previously hard to fit (Jennings et al., 2021).

Authors:Thorsten Balduin, Peter Woitke, Wing-Fai Thi, Uffe Gråe Jørgensen, Yasuhito Narita

Abstract: Protoplanetary disk are the foundation of planet formation. Lightning can have a profound impact on the chemistry of planetary atmospheres. The emergence of lightning in a similar manner in protoplanetary disks, would substantially alter the chemistry of protoplanetary disks. We aim to study under which conditions lightning could emerge within protoplanetary disks. We employ the ProDiMo code to make 2D thermo-chemical models of protoplanetary disks. We included a new way of how the code handles dust grains, which allows the consideration of dust grains of different sizes. We investigate the chemical composition, dust charging behaviour and charge balance of these models, to determine which regions could be most sufficient for lightning. We identify 6 regions within the disks where the charge balance is dominated by different radiation processes and find that the emergence of lightning is most probable in the lower and warmer regions of the midplane. This is due to the low electron abundance ($n_{\rm e}/n_{\rm\langle H \rangle}<10^{-15}$) in these regions and dust grains being the most abundant negative charge carriers ($ n_{\rm Z}/n_{\rm\langle H \rangle}> 10^{-13}$). We find that $\rm NH4^+$ is the most abundant positive charge carrier in those regions at the same abundances as the dust grains. We then develop a method of inducing electric fields via turbulence within this mix of dust grains and $\rm NH_4^+$. The electric fields generated with this mechanism are however several orders of magnitude weaker than required to overcome the critical electric field.

Authors:Bibiana Prinoth, H. Jens Hoeijmakers, Stefan Pelletier, Daniel Kitzmann, Brett M. Morris, Andreas Seifahrt, David Kasper, Heidi H. Korhonen, Madeleine Burheim, Jacob L. Bean, Björn Benneke, Nicholas W. Borsato, Madison Brady, Simon L. Grimm, Rafael Luque, Julian Stürmer, Brian Thorsbro

Abstract: Ultra-hot Jupiters are tidally locked with their host stars dividing their atmospheres into a hot dayside and a colder nightside. As the planet moves through transit, different regions of the atmosphere rotate into view revealing different chemical regimes. High-resolution spectrographs can observe asymmetries and velocity shifts, and offer the possibility for time-resolved spectroscopy. In this study, we search for other atoms and molecules in the planet`s transmission spectrum and investigate asymmetric signals. We analyse and combine eight transits of the ultra-hot Jupiter WASP-189 b taken with the HARPS, HARPS-N, ESPRESSO and MAROON-X high-resolution spectrographs. Using the cross-correlation technique, we search for neutral and ionised atoms, and oxides and compare the obtained signals to model predictions. We report significant detections for H, Na, Mg, Ca, Ca+, Ti, Ti+, TiO, V, Cr, Mn, Fe, Fe+, Ni, Sr, Sr+, and Ba+. Of these, Sr, Sr+, and Ba+ are detected for the first time in the transmission spectrum of WASP-189 b. In addition, we robustly confirm the detection of titanium oxide based on observations with HARPS and HARPS-N using the follow-up observations performed with MAROON-X and ESPRESSO. By fitting the orbital traces of the detected species by means of time-resolved spectroscopy using a Bayesian framework, we infer posterior distributions for orbital parameters as well as lineshapes. Our results indicate that different species must originate from different regions of the atmosphere to be able to explain the observed time dependence of the signals. Throughout the course of the transit, most signal strengths are expected to increase due to the larger atmospheric scale height at the hotter trailing terminator. For some species, however, the signals are instead observed to weaken due to ionisation for atoms and their ions, or the dissociation of molecules on the dayside.

Authors:Brian Jackson, Elisabeth R. Adams, Jeffrey P. Morgenthaler

Abstract: Tidal interactions between short-period exoplanets and their host stars drive orbital decay and have likely led to engulfment of planets by their stars. Precise transit timing surveys, with baselines now spanning decades for some planets, are directly detecting orbital decay for a handful of planets, with corroboration for planetary engulfment coming from independent lines of evidence. More than that, recent observations have perhaps even caught the moment of engulfment for one unfortunate planet. These portentous signs bolster prospects for ongoing surveys, but optimizing such a survey requires considering the astrophysical parameters that give rise to robust timing constraints and large tidal decay rates, as well as how best to schedule observations conducted over many years. The large number of possible targets means it is not feasible to continually observe all planets that might exhibit detectable tidal decay. In this study, we explore astrophysical and observational properties for a short-period exoplanet system that can maximize the likelihood for observing tidally driven transit-timing variations. We consider several fiducial observational strategies and real exoplanet systems reported to exhibit decay. We show that moderately frequent (a few transits per year) observations may suffice to detect tidal decay within just a few years. Tidally driven timing variations take time to grow to detectable levels, and so we estimate how long that growth takes as a function of timing uncertainties and tidal decay rate and provide thresholds for deciding that tidal decay has been detected.

Authors:Rodolfo Batista Negri, Antônio Fernando Bertachini de Almeida Prado

Abstract: This research investigates the influence of distant encounters between an asteroid and perturbing bodies on the deflection process, aiming to provide valuable guidelines for the trajectory design of a deflecting spacecraft. Analytical approximations are commonly used in the preliminary design phase to quickly explore a large design space. However, the dynamics involved in asteroid deflection are intricate, and simple models may not capture the full complexity of the system. We examine the accuracy and limitations of analytical models compared to more accurate numerical simulations. The study reveals that encounters with perturbing bodies, even at considerable distances (of dozens of radii of the sphere of influence), can significantly perturb the asteroid's trajectory, leading to discrepancies between analytical and numerical predictions. To address this, we propose a heuristic rule to guide trajectory designers in determining the suitability of analytical models for specific deflection scenarios. By understanding the impact of distant encounters on deflection, our study equips designers with the knowledge to make informed decisions during the trajectory planning process, facilitating efficient and effective asteroid deflection missions.

Authors:J. L. Ortiz, C. L. Pereira, B. Sicardy, F. Braga-Ribas, A. Takey, A. M. Fouad, A. A. Shaker, S. Kaspi, N. Brosch, M. Kretlow, R. Leiva, J. Desmars, B. E. Morgado, N. Morales, M. Vara-Lubiano, P. Santos-Sanz, E. Fernández-Valenzuela, D. Souami, R. Duffard, F. L. Rommel, Y. Kilic, O. Erece, D. Koseoglu, E. Ege, R. Morales, A. Alvarez-Candal, J. L. Rizos, J. M. Gómez-Limón, M. Assafin, R. Vieira-Martins, A. R. Gomes-Júnior, J. I. B. Camargo, J. Lecacheux

Abstract: We could accurately predict the shadow path and successfully observe an occultation of a bright star by Chiron on 2022 December 15. The Kottamia Astronomical Observatory in Egypt did not detect the occultation by the solid body, but we detected three extinction features in the light curve that had symmetrical counterparts with respect to the central time of the occultation. One of the features is broad and shallow, whereas the other two features are sharper with a maximum extinction of $\sim$25$\%$ at the achieved spatial resolution of 19 km per data point. From the Wise observatory in Israel, we detected the occultation caused by the main body and several extinction features surrounding the body. When all the secondary features are plotted in the sky plane we find that they can be caused by a broad $\sim$580 km disk with concentrations at radii of 325 \pm 16 km and 423 \pm 11 km surrounding Chiron. At least one of these structures appears to be outside the Roche limit. The ecliptic coordinates of the pole of the disk are $\lambda$ = 151$^\circ~\pm$ 8$^\circ$ and $\beta$ = 18$^\circ~\pm$ 11$^\circ$, in agreement with previous results. We also show our long-term photometry indicating that Chiron had suffered a brightness outburst of at least 0.6 mag between March and September 2021 and that Chiron was still somewhat brighter at the occultation date than at its nominal pre-outburst phase. The outermost extinction features might be consistent with a bound or temporarily bound structure associated with the brightness increase. However, the nature of the brightness outburst is unclear, and it is also unclear whether the dust or ice released in the outburst could be feeding a putative ring structure or if it emanated from it.

Authors:Danielle Bovie, A. C. Quillen, Rachel Glade

Abstract: In granular systems, thermal cycling causes compaction, creep, penetration of dense objects, and ratcheting of grains against each other. On asteroid surfaces, thermal cycling is high amplitude and can happen billions of times in a few million years. We use a 1-dimensional thermophysical conductivity model to estimate the relative displacement of grains in proximity to one another, caused by variations in thermal conductivity or shadows. We find that grains would experience relative displacements of order a few microns during each thermal cycle. If thermal cycling causes diffusive transport, then the asteroid's few centimeters deep thermal skin depth could flow a few centimeters in a million years. Thermal cycling could cause long-distance flows on sloped surfaces, allowing fine materials to collect in depressions.

Authors:Miti Patel, Cheyenne K. M. Polius, Matthew Ridsdill-Smith, Tim Lichtenberg, Richard Parker

Abstract: The presence of short-lived radioisotopes (SLRs) 26-Al and 60-Fe in the Solar system places constraints on the initial conditions of our planetary system. Most theories posit that the origin of 26-Al and 60-Fe is in the interiors of massive stars, and they are either delivered directly to the protosolar disc from the winds and supernovae of the massive stars, or indirectly via a sequential star formation event. However, massive stars that produce SLRs also emit photoionising far and extreme ultraviolet radiation, which can destroy the gas component of protoplanetary discs, possibly precluding the formation of gas giant planets like Jupiter and Saturn. Here, we perfom N-body simulations of star-forming regions and determine whether discs that are enriched in SLRs can retain enough gas to form Jovian planets. We find that discs are enriched and survive the photoionising radiation only when the dust radius of the disc is fixed and not allowed to move inwards due to the photoevaporation, or outwards due to viscous spreading. Even in this optimal scenario, not enough discs survive until the supernovae of the massive stars and so have zero or very little enrichment in 60-Fe. We therefore suggest that the delivery of SLRs to the Solar system may not come from the winds and supernovae of massive stars.

Authors:Małgorzata Królikowska, Luke Dones

Abstract: Context: Increasingly, Oort Cloud comets are being discovered at great distances from the Sun and tracked over ever wider ranges of heliocentric distances as observational equipment improves. Aims: To investigate in detail how the original semimajor axis for near-parabolic comets depends on the selected data arc and the assumed form of the non-gravitational (NG) acceleration. Methods: Among currently known Oort Cloud comets with large perihelion distances ($q > 3$ au), we selected 32 objects observed over the widest ranges of heliocentric distances in orbital legs before and after perihelion. For each of them, we determined a series of orbits using at least three basic types of data sets selected from available positional data (pre- and post-perihelion data and the entire data set), and a few forms of NG acceleration representing water ice or CO sublimation. Results: We found that the motion of comets is often measurably affected by NG forces at heliocentric distances beyond 5 au from the Sun. The most spectacular example is C/2010 U3 (Boattini), whose perihelion distance is 8.44 au. NG effects are detectable for 19 of the 32 comets within the positional data. For five comets, we found asymmetric effects of NG forces - in three cases significantly greater before perihelion than afterward (C/2017 M4, C/2000 SV$_{75}$, and C/2015 O1), and in two others the opposite (C/1997 BA$_6$ and C/2006 S3). We also find that the well-known systematic effect of finding more tightly bound original orbits when including the NG acceleration than in purely gravitational solutions may be related to the specific form of the standard $g(r)$ function describing the sublimation of ices.

Authors:Armando N. Perri, Fadia Taher, Laura K. McKemmish

Abstract: Zirconium monoxide (ZrO) absorption lines define rare S-type stars and are currently being sought on exoplanets. Successful detection is dependent on an accurate and comprehensive line list, with existing data not ideal for many applications. Specifically, the Plez \etal{} line list is near-complete but has insufficient accuracy for high-resolution cross-correlation, while the Sorensen \& Bernath data has high accuracy but only considers a small number of spectral bands. This article presents a novel spectroscopic model, variational line list and trihybrid line list for the main \ZrO{} isotopologue, as well as isotopologue-extrapolated hybrid line lists for the \isoa{}, \isob{}, \isoc{}, \isod{}~and \isoe{} isotopologues. These were constructed using \DUO{} based on icMRCI-SD/CASSCF~\abinitio{} electronic data calculated using \MOLPRO{}, experimental energies obtained from a previous \Marvel{} data compilation and perturbative energies from Sorensen \& Bernath. The new \ZrO{} \EXOMOL{}-style trihybrid line list, \LLname{}, comprises \noenergies{} energies (\noMaenergies{} experimental) and \notransitions{} transitions up to 30,000~\cm{} (333~nm) between ten low-lying electronic states (\ZrOX{}, \ZrOaa{}, \ZrOA{}, \ZrObb{}, \ZrOB{}, \ZrOC{}, \ZrOdd{}, \ZrOee{}, \ZrOff{} and \ZrOF{}). The inclusion of experimental energy levels in \LLname{} means ZrO will be much easier to detect using high-resolution ground-based telescopes in the 12,500 -- 17,500~\cm{} (571 -- 800~nm) spectral region. The inclusion of variational energy levels means that the ZorrO line list has very high completeness and can accurately model molecular absorption cross-sections even at high temperatures. The \LLname{} data will hopefully facilitate the first detection of ZrO in the atmosphere of a hot Jupiter exoplanet, or alternatively more conclusively exclude its presence.

Authors:S. M. Giuliatti Winter, G. Madeira, T. Ribeiro, O. C. Winter, G. O. Barbosa, G. Borderes-Motta

Abstract: Chariklo has two narrow and dense rings, C1R and C2R, located at 391 km and 405 km, respectively. In the light of new stellar occultation data, we study the stability around Chariklo. We also analyse three confinement mechanisms, to prevent the spreading of the rings, based on shepherd satellites in resonance with the edges of the rings. This study is made through a set of numerical simulations and the Poincar\'e surface of section technique. From the numerical simulation results we verify that, from the current parameters referring to the shape of Chariklo, the inner edge of the stable region is much closer to Chariklo than the rings. The Poincar\'e surface of sections allow us to identify the first kind periodic and quasi-periodic orbits, and also the resonant islands corresponding to the 1:2, 2:5, and 1:3 resonances. We construct a map of a versus e space which gives the location and width of the stable region and the 1:2, 2:5, and 1:3 resonances. We found that the first kind periodic orbits family can be responsible for a stable region whose location and size meet that of C1R, for specific values of the ring particles' eccentricities. However, C2R is located in an unstable region if the width of the ring is assumed to be about 120 m. After analysing different systems we propose that the best confinement mechanism is composed of three satellites, two of them shepherding the inner edge of C1R and the outer edge of C2R, while the third satellite would be trapped in the 1:3 resonance.

Authors:Madison Brady, Virginie Faramaz-Gorka, Geoffrey Bryden, Steve Ertel

Abstract: We present the results of N-body simulations meant to reproduce the long-term effects of mutually inclined exoplanets on debris disks, using the HD 202628 system as a proxy. HD 202628 is a Gyr-old solar-type star that possesses a directly observable, narrow debris ring with a clearly defined inner edge and non-zero eccentricity, hinting at the existence of a sculpting exoplanet. The eccentric nature of the disk leads us to examine the effect on it over Gyr timescales from an eccentric and inclined planet, placed on its orbit through scattering processes. We find that, in systems with dynamical timescales akin to that of HD 202628, a planetary companion is capable of completely tilting the debris disk. This tilt is preserved over the Gyr age of the system. Simulated observations of our models show that an exoplanet around HD 202628 with an inclination misalignment $\gtrsim\,10$ degrees would cause the disk to be observably diffuse and broad, which is inconsistent with ALMA observations. With these observations, we conclude that if there is an exoplanet shaping this disk, it likely had a mutual inclination of less than 5 degrees with the primordial disk. Conclusions of this work can be either applied to debris disks appearing as narrow rings (e.g., Fomalhaut, HR 4796), or to disks that are vertically thick at ALMA wavelengths (e.g., HD 110058).

Authors:Kellen Lawson, Joshua E. Schlieder, Jarron M. Leisenring, Ell Bogat, Charles A. Beichman, Geoffrey Bryden, András Gáspár, Tyler D. Groff, Michael W. McElwain, Michael R. Meyer, Thomas Barclay, Per Calissendorff, Matthew De Furio, Marie Ygouf, Anthony Boccaletti, Thomas P. Greene, John Krist, Peter Plavchan, Marcia J. Rieke, Thomas L. Roellig, John Stansberry, John P. Wisniewski, Erick T. Young

Abstract: High-contrast imaging of debris disk systems permits us to assess the composition and size distribution of circumstellar dust, to probe recent dynamical histories, and to directly detect and characterize embedded exoplanets. Observations of these systems in the infrared beyond 2--3 $\mu$m promise access to both extremely favorable planet contrasts and numerous scattered-light spectral features -- but have typically been inhibited by the brightness of the sky at these wavelengths. We present coronagraphy of the AU Microscopii (AU Mic) system using JWST's Near Infrared Camera (NIRCam) in two filters spanning 3--5 $\mu$m. These data provide the first images of the system's famous debris disk at these wavelengths and permit additional constraints on its properties and morphology. Conducting a deep search for companions in these data, we do not identify any compelling candidates. However, with sensitivity sufficient to recover planets as small as $\sim 0.1$ Jupiter masses beyond $\sim 2^{\prime\prime}$ ($\sim 20$ au) with $5\sigma$ confidence, these data place significant constraints on any massive companions that might still remain at large separations and provide additional context for the compact, multi-planet system orbiting very close-in. The observations presented here highlight NIRCam's unique capabilities for probing similar disks in this largely unexplored wavelength range, and provide the deepest direct imaging constraints on wide-orbit giant planets in this very well studied benchmark system.

Authors:Bingcheng Suo, A. C. Quillen, Max Neiderbach, Luke O'Brient, Abobakar Sediq Miakhel, Nathan Skerrett, Jérémy Couturier, Victor Lherm, Jiaxin Wang, Hesam Askari, Esteban Wright, Paul Sánchez

Abstract: We carry out experiments of 104 m/s velocity oblique impacts into a granular medium (sand). Impact craters have nearly round rims even at a grazing angle of about $10^\circ$, however, the strength of seismic pulses excited by the impact is dependent upon impact angle, and the ratio between uprange and downrange velocity peaks can be as large as 5, particularly at shallow depths. Crater slope, an offset between crater center and impact site, crater volume, azimuthal variation in ejection angle, seismic pulse shapes and subsurface flow direction are also sensitive to impact angle, but to a much lower degree than subsurface pulse strength. Uprange and downrange pulse peak amplitudes can be estimated from the horizontal and vertical components of the momentum imparted to the medium from the projectile

Authors:Arturo Miranda-Rosete Instituto de Ciencias Nucleares, UNAM, Antígona Segura Instituto de Ciencias Nucleares, UNAM Virtual Planet Laboratory, Edward W. Schwieterman Virtual Planet Laboratory University of California. Riverside Blue Marble Space Institute of Science

Abstract: Many past studies have predicted the steady-state production and maintenance of abiotic O$_2$ and O$_3$ in the atmospheres of CO$_2$-rich terrestrial planets orbiting M dwarf stars. However, the time-dependent responses of these planetary atmospheres to flare events - and the possible temporary production or enhancement of false positive biosignatures therein - has been comparatively less well studied. Most past works that have modeled the photochemical response to flares have assumed abundant free oxygen like that of the modern or Proterozoic Earth. Here we examine in detail the photochemical impact of the UV emitted by a single flare on abiotic O$_2$/O$_3$ production in prebiotic, CO$_2$-dominated atmospheres of M dwarf planets with CO$_2$ levels ranging from 10% to 90% of 1 bar. We find that a single flare generally destroys O$_2$ while modestly enhancing O$_3$ column densities. We simulate the spectral observables of both the steady-state atmosphere and time-dependent spectral response over the flare window for both emitted and transmitted light spectra. Over the course of the flare, the O$_3$ UV Hartley band is modestly enhanced by a maximum of 6 ppm while the CO$_2$ molecular transit depths modestly decline by 7 ppm. In both emitted and transmitted light spectra, the 9.65 $\mu$m O$_3$ band is hidden by the overlapping 9.4 $\mu$m CO$_2$ band for all scenarios considered. Overall, we find that the possible enhancements of abiotic O$_3$ due to a single flare are small compared to O$_3$'s sensitivity to other parameters such as CO$_2$ and H$_2$O abundances or the availability of reducing gases such as H$_2$.

Authors:T. Carter, M. Humi

Abstract: Current space exploration programs call for the establishment of a permanent Human presence on the Moon. This paper considers periodic orbits of a shuttle between the Earth and the Moon. Such a shuttle will be needed to bring supplies to the Moon outpost and carry back those resources that are in short supply on Earth. To keep this shuttle in permanent periodic orbit it must have a thruster that forces it into an elliptical orbit from perigee near Earth to an apogee just beyond the Moon and back to perigee. The impacts of the Earth, Moon and Sun gravity on this orbit are considered. For this model we determine the eccentricity that minimizes the thrust requirements and the lunar $\Delta\, v$ requirements. We show that optimal placements of the eccentricity of the shuttle orbit can produce significant improvement in thrust (and fuel) requirements.

Authors:Amedeo Balbi, Adam Frank

Abstract: On Earth, the development of technology required easy access to open air combustion, which is only possible when oxygen partial pressure, P(O$_2$), is above 18\%. This suggests that only planets with significant atmospheric oxygen concentrations will be capable of developing ``advanced'' technospheres and hence detectable technosignatures.

Authors:Ates Goksu Toronto, Taylor Kutra Toronto, Yanqin Wu Toronto

Abstract: Metal pollution onto white dwarfs is a wide-spread phenomenon that remains puzzling. Some of these white dwarfs also harbour gaseous debris disks. Their emission lines open a unique window to the physical properties of the polluting material, lending insights to their origin. Here, we model the emission line kinematics for the gas disk around SDSS J1228+1040, a system that has been continuously monitored for over two decades. Our model shows that the disk mass is strongly peaked at one solar radius (modulo the unknown inclination), and the disk eccentricity decreases from a value of 0.44 at the disk inner edge, to nearly zero at the outer edge. This eccentricity profile is exactly what one expects if the disk is in a global eccentric mode, precessing rigidly under the combined forces of general relativity and gas pressure, and with a period of 20 yrs. The gas disk contains a mass that is roughly equivalent to that of a 100-km rocky body, while the mass of the accompanying dust disk is likely insignificant. The disk eccentricity confirms an origin in tidal disruption, and we suggest that the disrupted body is sourced from a Mars-mass planetesimal disk within a few AU. More detailed analysis of this disk is warranted.

Authors:N. Hänni, K. Altwegg, D. Baklouti, M. Combi, S. A. Fuselier, J. De Keyser, D. R. Müller, M. Rubin, S. F. Wampfler

Abstract: The puzzling complexity of terrestrial biomolecules is driving the search for complex organic molecules in the Interstellar Medium (ISM) and serves as a motivation for many in situ studies of reservoirs of extraterrestrial organics from meteorites and interplanetary dust particles (IDPs) to comets and asteroids. Comet 67P/Churyumov-Gerasimenko (67P) -- the best-studied comet to date -- has been visited and accompanied for two years by the European Space Agency's Rosetta spacecraft. Around 67P's perihelion and under dusty conditions, the high-resolution mass spectrometer on board provided a spectacular glimpse into this comet's chemical complexity. For this work, we analyzed in unprecedented detail the O-bearing organic volatiles. In a comparison of 67P's inventory to molecules detected in the ISM, in other comets, and in Soluble Organic Matter (SOM) extracted from the Murchison meteorite, we also highlight the (pre)biotic relevance of different chemical groups of species. We report first evidence for abundant extraterrestrial O-bearing heterocycles (with abundances relative to methanol often on the order of 10% with a relative error margin of 30-50%) and various representatives of other molecule classes such as carboxylic acids and esters, aldehydes, ketones, and alcohols. Like with the pure hydrocarbons, some hydrogenated forms seem to be dominant over their dehydrogenated counterparts. An interesting example is tetrahydrofuran (THF) as it might be a more promising candidate for searches in the ISM than the long-sought furan itself. Our findings not only support and guide future efforts to investigate the origins of chemical complexity in space, but also they strongly encourage studies of, e.g., the ratios of unbranched vs. branched and hydrogenated vs. dehydrogenated species in astrophysical ice analogs in the laboratory as well as by modeling.

Authors:Daniel Sheward, Marco Delbo, Chrysa Avdellidou, Anthony Cook, Philippe Lognonné, Edhah Munabari, Luigi Zanatta, Antonio Mercatali, Silvano Delbo, Paolo Tanga

Abstract: Lunar impact flash (LIF) observations typically occur in R, I, or unfiltered light, and are only possible during night, targeting the night side of a 10-60% illumination Moon, while >10{\deg} above the observers horizon. This severely limits the potential to observe, and therefore the number of lower occurrence, high energy impacts observed is reduced. By shifting from the typically used wavelengths to the J-Band Short-Wave Infrared, the greater spectral radiance for the most common temperature (2750 K) of LIFs and darker skies at these wavelengths enables LIF monitoring to occur during the daytime, and at greater lunar illumination phases than currently possible. Using a 40.0 cm f/4.5 Newtonian reflector with Ninox 640SU camera and J-band filter, we observed several stars and lunar nightside at various times to assess the theoretical limits of the system. We then performed LIF observations during both day and night to maximise the chances of observing a confirmed LIF to verify the methods. We detected 61 >5{\sigma} events, from which 33 candidate LIF events could not be discounted as false positives. One event was confirmed by multi-frame detection, and by independent observers observing in visible light. While this LIF was observed during the night, the observed signal can be used to calculate the equivalent Signal-to-Noise ratio for a similar daytime event. The threshold for daylight LIF detection was found to be between Jmag=+3.4+-0.18 and Jmag=+5.6+-0.18 (Vmag=+4.5 and Vmag=+6.7 respectively at 2750 K). This represents an increase in opportunity to observe LIFs by almost 500%.

Authors:Keavin Moore, Nicolas B. Cowan, Charles-Édouard Boukaré

Abstract: Earth-like planets orbiting M-dwarf stars, M-Earths, are currently the best targets to search for signatures of life. Life as we know it requires water. The habitability of M-Earths is jeopardized by water loss to space: high flux from young M-dwarf stars can drive the loss of 3--20 Earth oceans from otherwise habitable planets. We develop a 0-D box model for Earth-mass terrestrial exoplanets, orbiting within the habitable zone, which tracks water loss to space and exchange between reservoirs during an early surface magma ocean phase and the longer deep-water cycling phase. A key feature is the duration of the surface magma ocean, assumed concurrent with the runaway greenhouse. This timescale can discriminate between desiccated planets, planets with desiccated mantles but substantial surface water, and planets with significant water sequestered in the mantle. A longer-lived surface magma ocean helps M-Earths retain water: dissolution of water in the magma provides a barrier against significant loss to space during the earliest, most active stage of the host M-dwarf, depending on the water saturation limit of the magma. Although a short-lived basal magma ocean can be beneficial to surface habitability, a long-lived basal magma ocean may sequester significant water in the mantle at the detriment of surface habitability. We find that magma oceans and deep-water cycling can maintain or recover habitable surface conditions on Earth-like planets at the inner edge of the habitable zone around late M-dwarf stars -- these planets would otherwise be desiccated if they form with less than ${\sim}$10 terrestrial oceans of water.

Authors:Tobias G. Meier, Dan J. Bower, Tim Lichtenberg, Mark Hammond, Paul J. Tackley

Abstract: The ultra-short-period super-Earth 55 Cancri e has a measured radius of 1.8 Earth radii. Previous thermal phase curve observations suggest a strong temperature contrast between the dayside and nightside of around 1000 K with the hottest point shifted $41\pm12$ degrees east from the substellar point, indicating some degree of heat circulation. The dayside (and potentially even the nightside) is hot enough to harbour a magma ocean. We use results from general circulation models (GCMs) of atmospheres to constrain the surface temperature contrasts. There is still a large uncertainty on the vigour and style of mantle convection in super-Earths, especially those that experience stellar irradiation large enough to harbour a magma ocean. In this work, we aim to constrain the mantle dynamics of the tidally locked lava world 55 Cancri e. Using the surface temperature contrasts as boundary condition, we model the mantle flow of 55 Cancri e using 2D mantle convection simulations and investigate how the convection regimes are affected by the different climate models. We find that large super-plumes form on the dayside if that hemisphere is covered by a magma ocean and the nightside remains solid or only partially molten. Cold material descends into the deep interior on the nightside, but no strong downwellings form. In some cases, the super-plume also moves several tens of degrees towards the terminator. A convective regime where the upwelling is preferentially on the dayside might lead to preferential outgassing on that hemisphere which could lead to the build-up of atmospheric species that could be chemically distinct from the nightside.

Authors:Natasha Latouf, Avi Mandell, Geronimo Villanueva, Michael Moore, Nicholas Susemiehl, Vincent Kofman, Michael Himes

Abstract: Detecting H2O in exoplanet atmospheres is the first step on the path to determining planet habitability. Coronagraphic design currently limits the observing strategy used to detect H2O, requiring the choice of specific bandpasses to optimize abundance constraints. In order to examing the optimal observing strategy for initial characterization of habitable planets using coronagraph-based direct imaging, we quantify the detectability of H2O as a function of signal-to-noise ratio (SNR) and molecular abundance across 25 bandpasses in the visible wavelength range (0.5-1 micron). We use a pre-constructed grid consisting of 1.4 million geometric albedo spectra across a range of abundance and pressure, and interpolate the produce forward models for an efficient nested sampling routine, PSGnest. We first test the detectability of H2O in atmospheres that mimix a modern-Earth twin, and then expand to examine a wider range of H2O abundances; for each abundance value, we constrain the optimal 20% bandpasses based on the effective signal-to-noise ratio (SNR) of the data. We present our findings of H2O detectability as functions of SNR, wavelength, and abundance, and discuss how to use these results for optimizing future coronographic instrument design. We find that there are specific points in wavelength where H2o can be detected down to 0.74 micron with moderate-SNR data for abundances at the upper end of Earth's presumed historical values, while at 0.9 micron, detectability is possible with low-SNR data at modern Earth abundances of H2O.

Authors:Inga Kamp, Thomas Henning, Aditya M. Arabhavi, Giulio Bettoni, Valentin Christiaens, Danny Gasman, Sierra L. Grant, Maria Morales-Calderón, Benoît Tabone, Alain Abergel, Olivier Absil, Ioannis Argyriou, David Barrado, Anthony Boccaletti, Jeroen Bouwman, Alessio Caratti o Garatti, Ewine F. van Dishoeck, Vincent Geers, Adrian M. Glauser, Manuel Güdel, Rodrigo Guadarrama, Hyerin Jang, Jayatee Kanwar, Pierre-Olivier Lagage, Fred Lahuis, Michael Mueller, Cyrine Nehmé, Göran Olofsson, Eric Pantin, Nicole Pawellek, Giulia Perotti, Tom P. Ray, Donna Rodgers-Lee, Matthias Samland, Silvia Scheithauer, Jürgen Schreiber, Kamber Schwarz, Milou Temmink, Bart Vandenbussche, Marissa Vlasblom, Christoffel Waelkens, L. B. F. M. Waters, Gillian Wright

Abstract: The understanding of planet formation has changed recently, embracing the new idea of pebble accretion. This means that the influx of pebbles from the outer regions of planet-forming disks to their inner zones could determine the composition of planets and their atmospheres. The solid and molecular components delivered to the planet-forming region can be best characterized by mid-infrared spectroscopy. With Spitzer low-resolution (R=100, 600) spectroscopy, this approach was limited to the detection of abundant molecules such as H2O, C2H2, HCN and CO2. This contribution will present first results of the MINDS (MIRI mid-IR Disk Survey, PI: Th. Henning) project. Due do the sensitivity and spectral resolution (R~1500-3500) provided by JWST we now have a unique tool to obtain the full inventory of chemistry in the inner disks of solar-types stars and brown dwarfs, including also less abundant hydrocarbons and isotopologues. The Integral Field Unit (IFU) capabilities enable at the same time spatial studies of the continuum and line emission in extended sources such as debris disks, the flying saucer and also the search for mid-IR signatures of forming planets in systems such as PDS70. These JWST observations are complementary to ALMA and NOEMA observations of the outer disk chemistry; together these datasets provide an integral view of the processes occurring during the planet formation phase.

Authors:Emily K. Deibert, Ernst J. W. de Mooij, Ray Jayawardhana, Jake D. Turner, Andrew Ridden-Harper, Callie E. Hood, Jonathan J. Fortney, Laura Flagg, Luca Fossati, Romain Allart, Matteo Brogi, Ryan J. MacDonald

Abstract: We present high-resolution transmission spectroscopy of WASP-76b with GRACES/Gemini North obtained as part of the ExoGemS survey. With a broad spectral range of 400-1050 nm and a relatively high resolution of ~66,000, these observations are particularly well-suited to searching for atomic and molecular atmospheric species via the Doppler cross-correlation technique. We recover absorption features due to neutral iron (Fe I), sodium (Na I), and ionized calcium (Ca II) at high significance (>5$\sigma$), and investigate possible atmospheric temperatures and wind speeds. We also report tentative (>3$\sigma$) detections of Li I, K I, Cr I, and V I in the atmosphere of WASP-76b. Finally, we report non-detections of a number of other species, some of which have previously been detected with other instruments. Through model injection/recovery tests, we demonstrate that many of these species are not expected to be detected in our observations. These results allow us to place GRACES and the ExoGemS survey in context with other high-resolution optical spectrographs.

Authors:Yisheng Tu, Zhi-Yun Li, Ka Ho Lam, Kengo Tomida, Chun-Yen Hsu

Abstract: Stars form from the gravitational collapse of turbulent, magnetized molecular cloud cores. Our non-ideal MHD simulations reveal that the intrinsically anisotropic magnetic resistance to gravity during the core collapse naturally generates dense gravo-magneto-sheetlets within inner protostellar envelopes -- disrupted versions of classical sheet-like pseudodisks. They are embedded in a magnetically dominant background, where less dense materials flow along the local magnetic field lines and accumulate in the dense sheetlets. The sheetlets, which feed the disk predominantly through its upper and lower surfaces, are the primary channels for mass and angular momentum transfer from the envelope to the disk. The protostellar disk inherits a small fraction (up to 10\%) of the magnetic flux from the envelope, resulting in a disk-averaged net vertical field strength of 1-10 mG and a somewhat stronger toroidal field, potentially detectable through ALMA Zeeman observations. The inherited magnetic field from the envelope plays a dominant role in disk angular momentum evolution, enabling the formation of gravitationally stable disks in cases where the disk field is relatively well-coupled to the gas. Its influence remains significant even in marginally gravitationally unstable disks formed in the more magnetically diffusive cases, removing angular momentum at a rate comparable to or greater than that caused by spiral arms. The magnetically driven disk evolution is consistent with the apparent scarcity of prominent spirals capable of driving rapid accretion in deeply embedded protostellar disks. The dense gravo-magneto-sheetlets observed in our simulations may correspond to the ``accretion streamers" increasingly detected around protostars.

Authors:Alex J. Meyer, Harrison F. Agrusa, Derek C. Richardson, R. Terik Daly, Oscar Fuentes-Muñoz, Masatoshi Hirabayashi, Patrick Michel, Colby C. Merrill, Ryota Nakano, Andrew F. Cheng, Brent Barbee, Olivier S. Barnouin, Steven R. Chesley, Carolyn M. Ernst, Ioannis Gkolias, Nicholas A. Moskovitz, Shantanu P. Naidu, Petr Pravec, Petr Scheirich, Cristina A. Thomas, Kleomenis Tsiganis, Daniel J. Scheeres

Abstract: With the successful impact of the NASA DART spacecraft in the Didymos-Dimorphos binary asteroid system, we provide an initial analysis of the post-impact perturbed binary asteroid dynamics. To compare our simulation results with observations, we introduce a set of "observable elements" calculated using only the physical separation of the binary asteroid, rather than traditional Keplerian elements. Using numerical methods that treat the fully spin-orbit-coupled dynamics, we estimate the system's mass and the impact-induced changes in orbital velocity, semimajor axis, and eccentricity. We find that the changes to the mutual orbit depend strongly on the separation distance between Didymos and Dimorphos at the time of impact. If Dimorphos enters a tumbling state after the impact, this may be observable through changes in the system's eccentricity and orbit period. We also find that any DART-induced reshaping of Dimorphos would generally reduce the required change in orbital velocity to achieve the measured post-impact orbit period and will be assessed by the ESA Hera mission in 2027.

Authors:Hiroshi Kobayashi, Hidekazu Tanaka

Abstract: Thanks to ``dust-to-planet'' simulations (DTPSs), which treat the collisional evolution directly from dust to giant-planet cores in a protoplanetary disk, we showed that giant-planet cores are formed in $\lesssim 10\,$au in several $10^5$ years, because porous pebbles grow into planetesimals via collisions prior to drift in 10 au (Kobayashi & Tanaka 2021, Paper I).However, such porous pebbles are unlikely to reproduce the polarized millimeter wavelength light observed from protoplanetary disks. We thus investigate gas-giant core formation with non-porous pebbles via DTPSs. Even non-porous bodies can grow into planetesimals and massive cores to be gas giants are also formed in several $10^5$ years. The rapid core formation is mainly via the accretion of planetesimals produced by collisional coagulation of pebbles drifting from the outer disk. The formation mechanism is similar to the case with porous pebbles, while core formation occurs in a wider region (5 - 10 au) than that with porous pebbles.

Authors:Yuna G. Kwon, Stefano Bagnulo, Alberto Cellino

Abstract: This study presents the first optical spectropolarimetric study of large C-complex asteroids. A total of 64 C-complex asteroids of different subclasses are analyzed using archival polarimetric and reflectance data to refine the link between polarimetric parameters and surface properties of the asteroids. We find a consistent difference in the polarization spectra between asteroids containing phyllosilicates and those without, which correlates with the overall morphology of the reflectance spectrum. They exhibit broad similarities in polarization-phase curves; nonetheless, we observe a gradual enhancement of the negative polarization branch in the ascending order of F-B-T-Ch types, along with an increase in reflectance curvature around 500 nm. Our observations suggest at least for large C-complex asteroids a common mechanism underlies the diversity in optical properties. The observed trends would be explained by the surface composition of the asteroids, particularly optical heterogeneity caused by carbon's varying levels of optical influence, primarily regulated by aqueous alteration of the surfaces.

Authors:Ya. N. Pavlyuchenkov, V. V. Akimkin, A. P. Topchieva, E. I. Vorobyov

Abstract: The thermal instability of accretion disks is widely used to explain the activity of cataclysmic variables, but its development in protoplanetary disks has been studied in less detail. We present a semi-analytical stationary model for calculating the midplane temperature of a gas and dust disk around a young star. The model takes into account gas and dust opacities, as well as the evaporation of dust at temperatures above 1000 K. Using this model, we calculate the midplane temperature distributions of the disk under various assumptions about the source of opacity and the presence of dust. We show that when all considered processes are taken into account, the heat balance equation in the region r<1 au has multiple temperature solutions. Thus, the conditions for thermal instability are met in this region. To illustrate the possible influence of instability on the accretion state in a protoplanetary disk, we consider a viscous disk model with alpha parameterization of turbulent viscosity. We show that in such a model the disk evolution is non-stationary, with alternating phases of accumulation of matter in the inner disk and its rapid accretion onto the star, leading to an episodic accretion pattern. These results indicate that this instability needs to be taken into account in evolutionary models of protoplanetary disks.

Authors:Zhu Liu, Duo Cui, Siyao Yang

Abstract: The experiment of exo-ecosystem and the exploration of extraterrestrial habitability aims to explore the adaptation of terrestrial life in space conditions for the manned space program and the future interstellar migration, which shows great scientific significance and public interests. By our knowledge the early life on Earth, archaea and extremophile have the ability to adapt to extreme environmental conditions and can potentially habitat in extraterrestrial environments. Here we proposed a design and framework for the experiment on exo-ecosystem and extraterrestrial habitability. The conceptual approach involves building an ecosystem based on archaea and extremophiles in a simulated extraterrestrial environment, with a focus on assessing the exobiological potential and adaptability of terrestrial life forms in such conditions through controlled experiments. Specifically, we introduce the Chinese Exo-Ecosystem Space Experiment (CHEESE), which investigates the survivability and potential for sustained growth, reproduction, and ecological interactions of methanogens under simulated Mars and Moon environments using the China Space Station (CSS) as a platform. We highlight that the space station provides unique yet relatively comprehensive conditions for simulating extraterrestrial environments. In conclusion, space experiments involving exo-ecosystems could pave the way for long-term human habitation in space, ensuring our ability to sustain colonies and settlements beyond Earth while minimizing our ecological impact on celestial bodies.

Authors:David Nesvorny, Luke Dones, Mario De Pra, Maria Womack, Kevin J. Zahnle

Abstract: Previous studies of cometary impacts in the outer Solar System used the spatial distribution of ecliptic comets (ECs) from dynamical models that assumed ECs began on low-inclination orbits (<5 deg) in the Kuiper belt. In reality, the source population of ECs - the trans-Neptunian scattered disk - has orbital inclinations reaching up to ~30 deg. In Nesvorny et al. (2017), we developed a new dynamical model of ECs by following comets as they evolved from the scattered disk to the inner Solar System. The model was absolutely calibrated from the population of Centaurs and active ECs. Here we use our EC model to determine the steady-state impact flux of cometary/Centaur impactors on Jupiter, Saturn, Uranus, and their moons. Relative to previous work (Zahnle et al. 2003), we find slightly higher impact probabilities on the outer moons and lower impact probabilities on the inner moons. The impact probabilities are smaller when comet disruption is accounted for. The results provide a modern framework for the interpretation of the cratering record in the outer Solar System.

Authors:Allona Vazan, Chris W. Ormel

Abstract: Sub-Neptune planets formed in the protoplanetary disk accreted hydrogen-helium (H,He) envelopes. Planet formation models of sub-Neptunes formed by pebble accretion result in small rocky cores surrounded by polluted H,He envelopes where most of the rock (silicate) is in vapor form at the end of the formation phase. This vapor is expected to condense and rain-out as the planet cools. In this Letter we examine the timescale for the rainout and its effect on the thermal evolution. We calculate the thermal and structural evolution of a 10 Earth masses planet formed by pebble accretion, taking into account material redistribution from silicate rainout (condensation and settling) and from convective mixing. We find that the duration of the rainout in sub-Neptunes is on Gyr timescale and varies with envelope mass: planets with envelopes below 0.75 Earth mass rainout into a core-envelope structure in less than 1 Gyr, while planets in excess of 0.75 Earth mass of H,He preserve some of their envelope pollution for billions of years. The energy released by the rainout inflates the radius with respect to planets that start out from a plain core-envelope structure. This inflation would result in estimates of the H,He contents of observed exoplanets based on the standard core-envelope structure to be too high.We identify a number of planets in the exoplanet census where rainout may operate, which would result in their H,He contents to be overestimated by up to a factor two. Future accurate age measurements by the PLATO mission may allow the identification of planets formed with polluted envelopes.

Authors:Ethan Carter, Dimitris Stamatellos

Abstract: The existence of giant planets on wide orbits ($\stackrel{>}{_\sim}100$AU) challenge planet formation theories; the core accretion scenario has difficulty in forming them, whereas the disc instability model forms an overabundance of them that is not seen observations. We perform $N$-body simulations investigating the effect of close stellar encounters ($\leq 1200$AU) on systems hosting wide-orbit giant planets and the extent at which such interactions may disrupt the initial wide-orbit planet population. We find that the effect of an interaction on the orbit of a planet is stronger for high-mass, low-velocity perturbers, as expected. We find that due to just a single encounter there is a $\sim 17%$ chance that the wide-orbit giant planet is liberated in the field, a $\sim 10$% chance it is scattered significantly outwards, and a $\sim 6$% chance it is significantly scattered inwards. Moreover, there is a $\sim 21\%$ chance that its eccentricity is excited to e>0.1, making it more prone to disruption in subsequent encounters. The results strongly suggest that the effect of even a single stellar encounter is significant in disrupting the primordial wide-orbit giant planet population; in reality the effect will be even more prominent, as in a young star-forming region more such interactions are expected to occur. We conclude that the low occurrence rate of wide-orbit planets revealed by observational surveys does not exclude the possibility that such planetary systems are initially abundant, and therefore the disc-instability model may be a plausible scenario for their formation.

Authors:Sebastiano Raffa, Gianmario Merisio, Francesco Topputo

Abstract: Trajectory design in highly-perturbed environments like binary asteroids is challenging. It typically requires using realistic, non-autonomous dynamical models in which periodic solutions vanish. In this work, a novel technique to find regions of bounded motion in the perturbed planar bi-elliptic restricted four-body problem is proposed. Lagrangian descriptors are employed to find regions of bounded motion about Dimorphos, the secondary body of the (65803) Didymos binary system. Results show that Lagrangian descriptors successfully reveal phase space organizing structures both in the unperturbed and perturbed planar bi-elliptic restricted four-body problem. With no solar radiation pressure, regions of bounded motion are visually identified, so granting access to a vast selection of bounded orbits about Dimorphos. Conversely, the presence of solar radiation pressure breaks down the majority of structures, leading to a large region of unstable motion with rare exceptions. Compared to other chaos indicators applied to the astrodynamics, Lagrangian descriptors are more convenient since they avoid propagating variational equations.

Authors:Keighley E. Rockcliffe, Elisabeth R. Newton, Allison Youngblood, Girish M. Duvvuri, Peter Plavchan, Peter Gao, Andrew W. Mann, Patrick J. Lowrance

Abstract: Photoevaporation is a potential explanation for several features within exoplanet demographics. Atmospheric escape observed in young Neptune-sized exoplanets can provide insight into and characterize which mechanisms drive this evolution and at what times they dominate. AU Mic b is one such exoplanet, slightly larger than Neptune (4.19 Earth radii). It closely orbits a 23 Myr pre-Main Sequence M dwarf with a period of 8.46 days. We obtained two visits of AU Mic b at Lyman-alpha with HST/STIS. One flare within the first HST visit is characterized and removed from our search for a planetary transit. We present a non-detection in our first visit followed by the detection of escaping neutral hydrogen ahead of the planet in our second visit. The outflow absorbed about 30% of the star's Lyman-alpha blue-wing 2.5 hours before the planet's white-light transit. We estimate the highest velocity escaping material has a column density of 10^13.96 cm^-2 and is moving 61.26 km/s away from the host star. AU Mic b's large high energy irradiation could photoionize its escaping neutral hydrogen in 44 minutes, rendering it temporarily unobservable. Our time-variable Lyman-alpha transit ahead of AU Mic b could also be explained by an intermediate stellar wind strength from AU Mic that shapes the escaping material into a leading tail. Future Lyman-alpha observations of this system will confirm and characterize the unique variable nature of its Lyman-alpha transit, which combined with modeling will tune the importance of stellar wind and photoionization.

Authors:Tatiana Demidova, Ivan Shevchenko

Abstract: Extensive numerical experiments on the long-term dynamics of planetesimals near the orbits of planets around single stars with debris disks have been carried out. The radial sizes of planetesimal clusters and the planetary chaotic zone as a function of mass parameter $\mu$ (planet-star mass ratio) have been determined numerically with a high accuracy separately for the outer and inner parts of the chaotic zone. The results obtained have been analyzed and interpreted in light of existing analytical theories (based on the planet-planetesimal mean motion resonance overlap criterion) and in comparison with previous numerical experiment approaches to the problem. We show and explain how the stepwise dependence of the chaotic zone sizes on $\mu$ is determined by the marginal resonances.

Authors:G. G. Michael, D. Tirsch, K. -D. Matz, W. Zuschneid, E. Hauber, K. Gwinner, S. Walter, R. Jaumann, T. Roatsch, F. Postberg

Abstract: The ever changing transparency of the Martian atmosphere hinders the determination of absolute surface colour from spacecraft images. While individual high resolution images from low orbit reveal numerous striking colour details of the geology, the colour variation between images caused by scattering off atmospheric dust can easily be of greater magni-tude. The construction of contiguous large-scale mosaics has thus required a strategy to suppress the influence of scatter-ing, most often a form of high-pass filtering, which limits their ability to convey colour variation information over distanc-es greater than the dimensions of single images. Here we make use of a dedicated high altitude observation campaign with the Mars Express High Resolution Stereo Camera1,2 (HRSC), applying a novel iterative method to construct a globally self-consistent colour model. We demonstrate that the model can be used to colour-reference a high-altitude mosaic in-corporating long-range colour variation information, and show that this mosaic, in turn, can be used to colour-reference high resolution images from low orbit. By using only the relative colour information internal to individual images, the in-fluence of absolute colour changes brought about by scattering is minimised, while the model iteration enables variations across image boundaries to be self-consistently reconstructed. The resulting mosaic reveals a previously unseen diversity and detail of colour, closely related to composition, over the whole of the martian surface.

Authors:Yuki K. Satoh, Naoki Koshimoto, David P. Bennett, Takahiro Sumi, Nicholas J. Rattenbury, Daisuke Suzuki, Shota Miyazaki, Ian A. Bond, Andrzej Udalski, Andrew Gould, Valerio Bozza, Martin Dominik, Yuki Hirao, Iona Kondo, Rintaro Kirikawa, Ryusei Hamada, Fumio Abe, Richard Barry, Aparna Bhattacharya, Hirosane Fujii, Akihiko Fukui, Katsuki Fujita, Tomoya Ikeno, Stela Ishitani Silva, Yoshitaka Itow, Yutaka Matsubara, Sho Matsumoto, Yasushi Muraki, Kosuke Niwa, Arisa Okamura, Greg Olmschenk, Clément Ranc, Taiga Toda, Mio Tomoyoshi, Paul J. Tristram, Aikaterini Vandorou, Hibiki Yama, Kansuke Yamashita, Przemek Mróz, Radosław Poleski, Jan Skowron, Michał K. Szymański, Radek Poleski, Igor Soszyński, Paweł Pietrukowicz, Szymon Kozłowski, Krzysztof Ulaczyk, Krzysztof A. Rybicki, Patryk Iwanek, Marcin Wrona, Mariusz Gromadzki, Michael D. Albrow, Sun-Ju Chung, Cheongho Han, Kyu-Ha Hwang, Doeon Kim, Youn Kil Jung, Hyoun Woo Kim, Yoon-Hyun Ryu, In-Gu Shin, Yossi Shvartzvald, Hongjing Yang, Jennifer C. Yee, Weicheng Zang, Sang-Mok Cha, Dong-Jin Kim, Seung-Lee Kim, Chung-Uk Lee, Dong-Joo Lee, Yongseok Lee, Byeong-Gon Park, Richard W. Pogge, Uffe G. Jørgensen, Penélope Longa-Peña, Sedighe Sajadian, Jesper Skottfelt, Colin Snodgrass, Jeremy Tregloan-Reed, Nanna Bach-Møller, Martin Burgdorf, Giuseppe D'Ago, Lauri Haikala, James Hitchcock, Markus Hundertmark, Elahe Khalouei, Nuno Peixinho, Sohrab Rahvar, John Southworth, Petros Spyratos

Abstract: We present an analysis of microlensing event OGLE-2019-BLG-0825. This event was identified as a planetary candidate by preliminary modeling. We find that significant residuals from the best-fit static binary-lens model exist and a xallarap effect can fit the residuals very well and significantly improves $\chi^2$ values. On the other hand, by including the xallarap effect in our models, we find that binary-lens parameters like mass-ratio, $q$, and separation, $s$, cannot be constrained well. However, we also find that the parameters for the source system like the orbital period and semi major axis are consistent between all the models we analyzed. We therefore constrain the properties of the source system better than the properties of the lens system. The source system comprises a G-type main-sequence star orbited by a brown dwarf with a period of $P\sim5$ days. This analysis is the first to demonstrate that the xallarap effect does affect binary-lens parameters in planetary events. It would not be common for the presence or absence of the xallarap effect to affect lens parameters in events with long orbital periods of the source system or events with transits to caustics, but in other cases, such as this event, the xallarap effect can affect binary-lens parameters.

Authors:Nicole Sobski, Sarah C. Millholland

Abstract: Compact systems of multiple close-in super-Earths/sub-Neptunes ("compact multis") are a ubiquitous outcome of planet formation. It was recently discovered that the outer edges of compact multis are located at smaller orbital periods than expected from geometric and detection biases alone, suggesting some truncation or transition in the outer architectures. Here we test whether this "edge-of-the-multis" might be explained in any part by distant giant planets in the outer regions ($\gtrsim 1$ AU) of the systems. We investigate the dynamical stability of observed compact multis in the presence of hypothetical giant ($\gtrsim 0.5 \ M_{\mathrm{Jup}}$) perturbing planets. We identify what parameters would be required for hypothetical perturbing planets if they were responsible for dynamically sculpting the outer edges of compact multis. "Edge-sculpting" perturbers are generally in the range $P\sim100-500$ days for the average compact multi, with most between $P\sim200-300$ days. Given the relatively close separation, we explore the detectability of the hypothetical edge-sculpting perturbing planets, finding that they would be readily detectable in transit and radial velocity data. We compare to observational constraints and find it unlikely that dynamical sculpting from distant giant planets contributes significantly to the edge-of-the-multis. However, this conclusion could be strengthened in future work by a more thorough analysis of the detection yields of the perturbing planets.

Authors:Yoon-Hyun Ryu, Andrzej Udalski, Jennifer C. Yee, Weicheng Zang, Yossi Shvartzvald, Cheongho Han, Andrew Gould, Michael D. Albrow, Sun-Ju Chung, Kyu-Ha Hwang, Youn Kil Jung, In-Gu Shin, Hongjing Yang, Sang-Mok Cha, Dong-Jin Kim, Seung-Lee Kim, Chung-Uk Lee, Dong-Joo Lee, Yongseok Lee, Byeong-Gon Park, Richard W. Pogge, Hanyue Wang, Przemek Mróz, Michał K. Szymański, Jan Skowron, Radek Poleski, Igor Soszyński, Paweł Pietrukowicz, Szymon Kozłowski, Krzysztof Ulaczyk, Krzysztof A. Rybicki, Patryk Iwanek, Marcin Wrona, Charles Beichman, Geoffry Bryden, Sean Carey, Calen B. Henderson, Sebastiano Calchi Novati, Wei Zhu, Savannah Jacklin, Matthew T. Penny

Abstract: We complete the analysis of planetary candidates found by the KMT AnomalyFinder for the 2017 prime fields that cover $\sim 13\,{\rm deg}^2$. We report 3 unambiguous planets: OGLE-2017-BLG-0640, OGLE-2017-BLG-1275, and OGLE-2017-BLG-1237. The first two of these were not previously identified, while the last was not previously published due to technical complications induced by a nearby variable. We further report that a fourth anomalous event, the previously recognized OGLE-2017-BLG-1777, is very likely to be planetary, although its light curve requires unusually complex modeling because the lens and source both have orbiting companions. One of the 3 unambiguous planets, OGLE-2017-BLG-1275 is the first AnomalyFinder discovery that has a {\it Spitzer} microlens parallax measurement, $\pi_E \sim 0.045\pm0.015$, implying that this planetary system almost certainly lies in the Galactic bulge. In the order listed, the four planetary events have planet-host mass ratios $q$, and normalized projected separations $s$, of $(\log q,s)$ = $(-2.31,0.61)$, $(-2.06,0.63/1.09)$, $(-2.10,1.04)$, and $(-2.86,0.72)$. Combined with previously published events, the 2017 AnomalyFinder prime fields contain 11 unambiguous planets with well-measured $q$ and one very likely candidate, of which 3 are AnomalyFinder discoveries. In addition to these 12, there are three other unambiguous planets with large uncertainties in $q$.

Authors:P. Weber, S. Pérez, A. Zurlo, J. Miley, A. Hales, L. Cieza, D. Principe, M. Cárcamo, A. Garufi, Á. Kóspál, M. Takami, J. Kastner, Z. Zhu, J. Williams

Abstract: The formation of giant planets has traditionally been divided into two pathways: core accretion and gravitational instability. However, in recent years, gravitational instability has become less favored, primarily due to the scarcity of observations of fragmented protoplanetary disks around young stars and low occurrence rate of massive planets on very wide orbits. In this study, we present a SPHERE/IRDIS polarized light observation of the young outbursting object V960 Mon. The image reveals a vast structure of intricately shaped scattered light with several spiral arms. This finding motivated a re-analysis of archival ALMA 1.3 mm data acquired just two years after the onset of the outburst of V960 Mon. In these data, we discover several clumps of continuum emission aligned along a spiral arm that coincides with the scattered light structure. We interpret the localized emission as fragments formed from a spiral arm under gravitational collapse. Estimating the mass of solids within these clumps to be of several Earth masses, we suggest this observation to be the first evidence of gravitational instability occurring on planetary scales. This study discusses the significance of this finding for planet formation and its potential connection with the outbursting state of V960 Mon.

Authors:Francisco J. T. Salazar, Antonio F. B. A. Prado

Abstract: This study focuses on attitude and control motion of two bodies (a base-satellite and a sub-satellite) connected by an inextensible and massless tether in a circular orbit under the influence of the Earths gravitational force. The base-satellite is assumed to be far more heavier than the sub-satellite. In such cases, the base-satellite is regarded as the reference spacecraft. Because of the complexity of the problem, no thrusters on the sub-satellite are considered, and the effect of atmospheric drag, Earths oblateness, and electrodynamic force on the spacecraft are neglected.

Authors:Richard G. French, Damya Souami

Abstract: In support of studies of decadal-timescale evolution of outer solar system atmospheres and ring systems, we present detailed Earth-based stellar occultation predictions for Jupiter, Saturn, Uranus, Neptune, Titan, and Triton for 2023-2050, based on the Gaia DR3 star catalog and near-IR K-band photometry from the 2MASS catalog. We tabulate the number of observable events by year and magnitude interval, reflecting the highly variable frequency of high-SNR events depending on the target's path relative to the star-rich regions of the Milky Way. We identify regions on Earth where each event is potentially observable, and for atmospheric occultations, we determine the latitude of the ingress and egress events. For Saturn, Uranus, and Neptune, we also compute the predicted ring occultation event times. We present representative subsets of the predicted events and highlights particularly promising events. Jupiter occultations with K $\leq$7 occur at a cadence of about one per year, with bright events at higher frequency in 2031 and 2043. Saturn occultations are much rarer, with only two predicted events with K $\leq$5 in 2032 and 2047. Ten Uranus ring occultations are predicted with K$\leq$10 for the period 2023 to 2050. Neptune traverses star-poor regions of the sky until 2068, resulting in only 13 predicted occultations for K$\leq$12 between 2023 and 2050. Titan has several high-SNR events between 2029--2031, whereas Triton is limited to a total of 22 occultations with K$\leq$15 between 2023 and 2050. Details of all predicted events are included in the Supplementary Online Material.

Authors:Fabo Feng, R. Paul Butler, Steven S. Vogt, Jennifer Burt, Bradford Holden, Yicheng Rui

Abstract: With its near-to-mid-infrared high contrast imaging capabilities, JWST is ushering us into a golden age of directly imaging Jupiter-like planets. As the two closest cold Jupiters, $\varepsilon$ Ind A b and $\varepsilon$ Eridani b have sufficiently wide orbits and adequate infrared emissions to be detected by JWST. To detect more Jupiter-like planets for direct imaging, we develop a GOST-based method to analyze radial velocity data and multiple Gaia data releases simultaneously. Without approximating instantaneous astrometry by catalog astrometry, this approach enables the use of multiple Gaia data releases for detection of both short-period and long-period planets. We determine a mass of $2.96_{-0.38}^{+0.41}$ $M_{\rm Jup}$ and a period of $42.92_{-4.09}^{+6.38}$ yr for $\varepsilon$ Ind A b. We also find a mass of $0.76_{-0.11}^{+0.14}$ $M_{\rm Jup}$, a period of $7.36_{-0.05}^{+0.04}$ yr, and an eccentricity of 0.26$_{-0.04}^{+0.04}$ for $\varepsilon$ Eridani b. The eccentricity differs from that given by some previous solutions probably due to the sensitivity of orbital eccentricity to noise modeling. Our work refines the constraints on orbits and masses of the two nearest Jupiters and demonstrate the feasibility of using multiple Gaia data releases to constrain Jupiter-like planets.

Authors:Kenji Kurosaki, Shu-ichiro Inutsuka

Abstract: Numerous exoplanets with masses ranging from Earth to Neptune and radii larger than Earth have been found through observations. These planets possess atmospheres that range in mass fractions from 1% to 30%, reflecting the diversity of atmospheric mass fractions. Such diversities are supposed to be caused by differences in the formation processes or evolution. Here we consider head-on giant impacts onto planets causing atmosphere losses in the later stage of their formation. We perform smoothed particle hydrodynamic simulations to study the impact-induced atmosphere loss of young super-Earths with 10%-30% initial atmospheric mass fractions. We find that the kinetic energy of the escaping atmosphere is almost proportional to the sum of the kinetic impact energy and self-gravitational energy released from the merged core. We derive the relationship between the kinetic impact energy and the escaping atmosphere mass. The giant impact events for planets of comparable masses are required in the final stage of the popular scenario of rocky planet formation. We show it results in a significant loss of the atmosphere, if the impact is a head-on collision with comparable masses. This latter fact provides a constraint on the formation scenario of rocky planets with substantial atmospheres.

Authors:Olga Balsalobre-Ruza, Itziar de Gregorio-Monsalvo, Jorge Lillo-Box, Nuria Huélamo, Álvaro Ribas, Myriam Benisty, Jaehan Bae, Stefano Facchini, Richard Teague

Abstract: Context: High-spatial resolution Atacama Large Millimeter/submillimeter Array (ALMA) data have revealed a plethora of substructures in protoplanetary disks. Some of those features are thought to trace the formation of embedded planets. One example is the gas and dust that accumulated in the co-orbital Lagrangian regions $L_4$/$L_5$, which were tentatively detected in recent years and might be the pristine material for the formation of Trojan bodies. Aims: This work is part of the TROY project, whose ultimate goal is to find robust evidence of exotrojan bodies and study their implications in the exoplanet field. Here, we focus on the early stages of the formation of these bodies by inspecting the iconic system PDS 70, the only confirmed planetary system in formation. Methods: We reanalyzed archival high-angular resolution Band 7 ALMA observations from PDS 70 by doing an independent imaging process to look for emission in the Lagrangian regions of the two detected gas giant protoplanets, PDS 70 b and c. We then projected the orbital paths and visually inspected emission features at the regions around the $L_4$/$L_5$ locations as defined by $\pm$ 60$^{\circ}$ in azimuth from the planet position. Results: We found emission at a $\sim$4-$\sigma$ level ($\sim$6-$\sigma$ when correcting from a cleaning effect) at the position of the $L_{5}$ region of PDS 70 b. This emission corresponds to a dust mass in a range of 0.03- 2 M$_{Moon}$, which potentially accumulated in this gravitational well. Conclusions: The tentative detection of the co-orbital dust trap that we report requires additional observations to be confirmed. We predict that we could detect the co-orbital motion of PDS 70 b and the dust presumably associated with $L_5$ by observing again with the same sensitivity and angular resolution as early as February 2026.

Authors:Athul Pradeepkumar Girija

Abstract: The ability to launch small secondary payloads to Mars on future science missions present an exciting opportunity for demonstration of advanced technologies for planetary exploration such as aerocapture. Over the years, several aerocapture technology demonstration missions have been proposed but none could be realized, causing the technology to become dormant as it is seen as too risky and expensive to be used on a science mission. The present study proposes a low-cost Mars aerocapture demonstration concept as a secondary payload, and could pave the way for future low-cost small interplanetary orbiter missions. The proposed mission heavily leverages the mission architecture and the flight hardware of the MarCO spacecraft for a low cost mission. The 35 kg technology demonstrator would launch as an ESPA secondary payload on a future Mars mission, and would be deployed from the upper stage soon after primary spacecraft separation. The vehicle then independently cruises to Mars, where it will perform aerocapture and insert a 6U MarCO heritage CubeSat to a 200 x 2000 km orbit. The mission architecture incorporates a number of cost saving approaches, and is estimated to fit within a 30M cost cap, of which 10M is allocated for technology development and risk reduction.

Authors:Maria N. Drozdovskaya, Dominique Bockelée-Morvan, Jacques Crovisier, Brett A. McGuire, Nicolas Biver, Steven B. Charnley, Martin A. Cordiner, Stefanie N. Milam, Cyrielle Opitom, Anthony J. Remijan

Abstract: A lower-than-solar elemental nitrogen content has been demonstrated for several comets, including 1P/Halley and 67P/C-G with independent in situ measurements of volatile and refractory budgets. The recently discovered semi-refractory ammonium salts in 67P/C-G are thought to be the missing nitrogen reservoir in comets. The thermal desorption of ammonium salts from cometary dust particles leads to their decomposition into ammonia and a corresponding acid. The NH$_{3}$/H$_{2}$O ratio is expected to increase with decreasing heliocentric distance with evidence for this in near-infrared observations. NH$_{3}$ has been claimed to be more extended than expected for a nuclear source. Here, the aim is to constrain the NH$_{3}$/H$_{2}$O ratio in comet C/2020 F3 (NEOWISE) during its July 2020 passage. OH emission from comet C/2020 F3 (NEOWISE) was monitored for 2 months with NRT and observed from GBT on 24 July and 11 August 2020. Contemporaneously with the 24 July 2020 OH observations, the NH$_{3}$ hyperfine lines were targeted with GBT. The concurrent GBT and NRT observations allowed the OH quenching radius to be determined at $\left(5.96\pm0.10\right)\times10^{4}$ km on 24 July 2020, which is important for accurately deriving $Q(\text{OH})$. C/2020 F3 (NEOWISE) was a highly active comet with $Q(\text{H}_{2}\text{O}) \approx 2\times10^{30}$ molec s$^{-1}$ one day before perihelion. The $3\sigma$ upper limit for $Q_{\text{NH}_{3}}/Q_{\text{H}_{2}\text{O}}$ is $<0.29\%$ at $0.7$ au from the Sun. The obtained NH$_{3}$/H$_{2}$O ratio is a factor of a few lower than measurements for other comets at such heliocentric distances. The abundance of NH$_{3}$ may vary strongly with time depending on the amount of water-poor dust in the coma. Lifted dust can be heated, fragmented, and super-heated; whereby, ammonium salts, if present, can rapidly thermally disintegrate and modify the NH$_{3}$/H$_{2}$O ratio.

Authors:David J. Armstrong, Ares Osborn, Vardan Adibekyan, Elisa Delgado-Mena, Saeed Hojjatpanah, Steve B. Howell, Sergio Hoyer, Henrik Knierim, Sérgio G. Sousa, Keivan G. Stassun, Dimitri Veras, David R. Anderson, Daniel Bayliss, François Bouchy, Christopher J. Burke, Jessie L. Christiansen, Xavier Dumusque, Marcelo Aron Fetzner Keniger, Andreas Hadjigeorghiou, Faith Hawthorn, Ravit Helled, Jon M. Jenkins, David W. Latham, Jorge Lillo-Box, Louise D. Nielsen, Hugh P. Osborn, José Rodrigues, David Rodriguez, Nuno C. Santos, Sara Seager, Paul A. Strøm, Guillermo Torres, Joseph D. Twicken, Stephane Udry, Peter J. Wheatley, Joshua N. Winn

Abstract: We report the discovery of two exoplanets orbiting around HD 212729 (TOI\,1052, TIC 317060587), a $T_{\rm eff}=6146$K star with V=9.51 observed by TESS in Sectors 1 and 13. One exoplanet, TOI-1052b, is Neptune-mass and transits the star, and an additional planet TOI-1052c is observed in radial velocities but not seen to transit. We confirm the planetary nature of TOI-1052b using precise radial velocity observations from HARPS and determined its parameters in a joint RV and photometry analysis. TOI-1052b has a radius of $2.87^{+0.29}_{-0.24}$ R$_{\oplus}$, a mass of $16.9\pm 1.7$ M$_{\oplus}$, and an orbital period of 9.14 days. TOI-1052c does not show any transits in the TESS data, and has a minimum mass of $34.3^{+4.1}_{-3.7}$ M$_{\oplus}$ and an orbital period of 35.8 days, placing it just interior to the 4:1 mean motion resonance. Both planets are best fit by relatively high but only marginally significant eccentricities of $0.18^{+0.09}_{-0.07}$ for planet b and $0.24^{+0.09}_{-0.08}$ for planet c. We perform a dynamical analysis and internal structure model of the planets as well as deriving stellar parameters and chemical abundances. The mean density of TOI-1052b is $3.9^{+1.7}_{-1.3}$ g cm$^{-3}$ consistent with an internal structure similar to Neptune. A nearby star is observed in Gaia DR3 with the same distance and proper motion as TOI-1052, at a sky projected separation of ~1500AU, making this a potential wide binary star system.

Authors:C. Moutou, X. Delfosse, A. C. Petit, J. -F. Donati, E. Artigau, P. Fouque, A. Carmona, M. Ould-Elhkim, L. Arnold, N. J. Cook, C. Cadieux, S. Bellotti, I. Boisse, F. Bouchy, P. Charpentier, P. Cortes-Zuleta, R. Doyon, G. Hebrard, E. Martioli, J. Morin, T. Vandal

Abstract: SPIRou is a near-infrared spectropolarimeter and a high-precision velocimeter. The SPIRou Legacy Survey collected data from February 2019 to June 2022, half of the time devoted to a blind search for exoplanets around nearby cool stars. The aim of this paper is to present this program and an overview of its properties, and to revisit the radial velocity (RV) data of two multiplanet systems, including new visits with SPIRou. From SPIRou data, we can extract precise RVs using efficient telluric correction and line-by-line measurement techniques, and we can reconstruct stellar magnetic fields from the collection of polarized spectra using the Zeeman-Doppler imaging method. The stellar sample of our blind search in the solar neighborhood, the observing strategy, the RV noise estimates, chromatic behavior, and current limitations of SPIRou RV measurements on bright M dwarfs are described. In addition, SPIRou data over a 2.5-year time span allow us to revisit the known multiplanet systems GJ~876 and GJ~1148. For GJ~876, the new dynamical analysis including the four planets is consistent with previous models and confirms that this system is deep in the Laplace resonance and likely chaotic. The large-scale magnetic map of GJ~876 over two consecutive observing seasons is obtained and shows a dominant dipolar field with a polar strength of 30~G, which defines the magnetic environment in which the inner planet with a period of 1.94~d is embedded. For GJ~1148, we refine the known two-planet model.

Authors:F. Lesjak, L. Nortmann, F. Yan, D. Cont, A. Reiners, N. Piskunov, A. Hatzes, L. Boldt-Christmas, S. Czesla, U. Heiter, O. Kochukhov, A. Lavail, E. Nagel, A. D. Rains, M. Rengel, F. Rodler, U. Seemann, D. Shulyak

Abstract: Accurately estimating the C/O ratio of hot Jupiter atmospheres is a promising pathway towards understanding planet formation and migration, as well as the formation of clouds and the overall atmospheric composition. The atmosphere of the hot Jupiter WASP-43b has been extensively analysed using low-resolution observations with HST and Spitzer, but these previous observations did not cover the K band, which hosts prominent spectral features of major carbon-bearing species such as CO and CH$_{4}$. As a result, the ability to establish precise constraints on the C/O ratio was limited. Moreover, the planet has not been studied at high spectral resolution, which can provide insights into the atmospheric dynamics. In this study, we present the first high-resolution dayside spectra of WASP-43b with the new CRIRES$^+$ spectrograph. By observing the planet in the K band, we successfully detected the presence of CO and provide evidence for the existence of H$_2$O using the cross-correlation method. This discovery represents the first direct detection of CO in the atmosphere of WASP-43b. Furthermore, we retrieved the temperature-pressure profile, abundances of CO and H$_2$O, and a super-solar C/O ratio of 0.78 by applying a Bayesian retrieval framework to the data. Our findings also shed light on the atmospheric characteristics of WASP-43b. We found no evidence for a cloud deck on the dayside, and recovered a line broadening indicative of an equatorial super-rotation corresponding to a jet with a wind speed of $\sim$ 5 km s$^{-1}$, matching the results of previous forward models and low-resolution atmospheric retrievals for this planet.

Authors:Ada Canet, Ana I. Gómez De Castro

Abstract: Forming planets around young, fast-rotating solar-like stars are exposed to an intense X-ray/extreme ultraviolet radiation field and strongly magnetized stellar winds, as a consequence of the high magnetic activity of these stars. Under these conditions, Earth-like exoplanets may experience a rapid loss of their primordial hydrogen atmospheres, resulting in atmosphere-less rocky obstacles for the stellar winds. The interaction of stellar winds with those planets leads to the formation of potentially observable structures due to the formation of large-scale magnetic field and density disturbances in the vicinity of these planets, such as bow shocks, induced magnetospheres and comet-like tails. In this work, we study the interaction between the stellar winds of active, fast-rotating solar-like stars in the superfast-magnetosonic regime with Earth-like, unmagnetized, tenuous atmosphere, planetary obstacles through numerical 3D simulations using the PLUTO magnetohydrodynamical code. The properties of AB Doradus, a nearby young star with a small rotation period (0.51 days) and a strong flaring activity, have been used to parameterize this early wind state. Bow shock and induced magnetosphere formation are characterized through the alfv\'enic Mach number MA of the wind, for different stellar wind configurations. Large bow shocks, up to an extension of ~7.0 planetary radii are found for low-MA winds. The general increase of density, temperature and magnetic field in these large-scale structures formed around planets may result in potentially detectable spectral signatures.

Authors:Pietro Curone, Leonardo Testi, Enrique Macias, Marco Tazzari, Stefano Facchini, Jonathan P. Williams, Cathie J. Clarke, Antonella Natta, Giovanni Rosotti, Claudia Toci, Giuseppe Lodato

Abstract: Protoplanetary disks emit radiation across a broad range of wavelengths, requiring a multiwavelength approach to fully understand their physical mechanisms and how they form planets. Observations at sub-millimeter to centimeter wavelengths can provide insights into the thermal emission from dust, free-free emission from ionized gas, and possible gyro-synchrotron emission from the stellar magnetosphere. This Letter focuses on CX Tau, a ${\sim}0.4\,M_\odot$ star with an extended gas emission and a compact and apparently structureless dust disk, with an average millimeter flux when compared to Class II sources in Taurus. We present Karl G. Jansky Very Large Array (VLA) observations in 4 bands (between 9.0 mm and 6.0 cm) and combine them with archival data from the Atacama Large Millimeter/submillimeter Array (ALMA), the Submillimeter Array (SMA) and the Plateau de Bure Interferometer (PdBI). Such a multiwavelength approach allows to separate the dust continuum from other emissions. After isolating the dust thermal emission, we derived an upper limit of the dust disk extent at 1.3 cm which is consistent with theoretical predictions of a radial drift-dominated disk. Centimeter data show a peculiar behavior: deep observations at 6.0 cm did not detect the source, while at 1.3 cm the flux density is anomalously higher than adjacent bands. Intraband spectral indices suggest a dominant contribution from free-free emission, whereas gyro-synchrotron emission is excluded. To explain these observations, we propose strong variability of the free-free emission with timescales shorter than a month. Another possible interpretation is the presence of anomalous microwave emission from spinning dust grains.

Authors:Maureen Cohen, Paul I. Palmer, Adiv Paradise, Massimo A. Bollasina, Paola Ines Tiranti

Abstract: Transmission spectroscopy supports the presence of uncharacterised, light-scattering and -absorbing aerosols in the atmospheres of many exoplanets. The complexity of factors influencing the formation, 3-D transport, radiative impact, and removal of aerosols makes it challenging to match theoretical models to the existing data. Our study simplifies these factors to focus on the interaction between planetary general circulation and haze distribution at the planetary limb. We use an intermediate complexity general circulation model, ExoPlaSim, to simulate idealised organic haze particles as radiatively active tracers in the atmospheres of tidally locked terrestrial planets for 32 rotation rates. We find three distinct 3-D spatial haze distributions, corresponding to three circulation regimes, each with a different haze profile at the limb. All regimes display significant terminator asymmetry. In our parameter space, super-Earth-sized planets with rotation periods greater than 13 days have the lowest haze optical depths at the terminator, supporting the choice of slower rotators as observing targets.

Authors:J. J. Zanazzi, Eugene Chiang

Abstract: The orbits of some warm Jupiters are highly inclined (20$^\circ$-50$^\circ$) to those of their exterior companions. Comparable misalignments are inferred between the outer and inner portions of some transition discs. These large inclinations may originate from planet-planet and planet-disc secular resonances that sweep across interplanetary space as parent discs disperse. The maximum factor by which a seed mutual inclination can be amplified is of order the square root of the angular momentum ratio of the resonant pair. We identify those giant planet systems (e.g. Kepler-448 and Kepler-693) which may have crossed a secular resonance, and estimate the required planet masses and semimajor axes in transition discs needed to warp their innermost portions (e.g. in CQ Tau). Passage through an inclination secular resonance could also explain the hypothesized large mutual inclinations in apsidally-orthogonal warm Jupiter systems (e.g. HD 147018).

Authors:Nicholas F. Wogan, David C. Catling, Kevin J. Zahnle, Roxana Lupu

Abstract: The origin of life on Earth would benefit from a prebiotic atmosphere that produced nitriles, like HCN, which enable ribonucleotide synthesis. However, geochemical evidence suggests that Hadean air was relatively oxidizing with negligible photochemical production of prebiotic molecules. These paradoxes are resolved by iron-rich asteroid impacts that transiently reduced the entire atmosphere, allowing nitriles to form in subsequent photochemistry. Here, we investigate impact-generated reducing atmospheres using new time-dependent, coupled atmospheric chemistry and climate models, which account for gas-phase reactions and surface-catalysis. The resulting H$_2$-, CH$_4$- and NH$_3$-rich atmospheres persist for millions of years, until hydrogen escapes to space. HCN and HCCCN production and rainout to the surface can reach $10^9$ molecules cm$^{-2}$ s$^{-1}$ in hazy atmospheres with a mole ratio of $\mathrm{CH_4} / \mathrm{CO_2} > 0.1$. Smaller $\mathrm{CH_4} / \mathrm{CO_2}$ ratios produce HCN rainout rates $< 10^5$ molecules cm$^{-2}$ s$^{-1}$, and negligible HCCCN. The minimum impactor mass that creates atmospheric $\mathrm{CH_4} / \mathrm{CO_2} > 0.1$ is $4 \times 10^{20}$ to $5 \times 10^{21}$ kg (570 to 1330 km diameter), depending on how efficiently iron reacts with a steam atmosphere, the extent of atmospheric equilibration with an impact-induced melt pond, and the surface area of nickel that catalyzes CH$_4$ production. Alternatively, if steam permeates and deeply oxidizes crust, impactors $\sim 10^{20}$ kg could be effective. Atmospheres with copious nitriles have $> 360$ K surface temperatures, perhaps posing a challenge for RNA longevity, although cloud albedo can produce cooler climates. Regardless, post-impact cyanide can be stockpiled and used in prebiotic schemes after hydrogen has escaped to space.

Authors:Fernando Moreno, Adriano Campo Bagatin, Gonzalo Tancredi, Jian-Yang Li, Alessandro Rossi, Fabio Ferrari, Masatoshi Hirabayashi, Eugene Fahnestock, Alain Maury, Robert Sandness, Andrew S. Rivkin, Andy Cheng, Tony L. Farnham, Stefania Soldini, Carmine Giordano, Gianmario Merisio, Paolo Panicucci, Mattia Pugliatti, Alberto J. Castro-Tirado, Emilio Fernandez-Garcia, Ignacio Perez-Garcia, Stavro Ivanovski, Antti Penttila, Ludmilla Kolokolova, Javier Licandro, Olga Munoz, Zuri Gray, Jose L. Ortiz, Zhong-Yi Lin

Abstract: The NASA/DART (Double Asteroid Redirection Test) spacecraft successfully crashed on Dimorphos, the secondary component of the binary (65803) Didymos system. Following the impact, a large dust cloud was released, and a long-lasting dust tail was developed. We have extensively monitored the dust tail from the ground and from the Hubble Space Telescope (HST). We provide a characterization of the ejecta dust properties, i.e., particle size distribution and ejection speeds, ejection geometric parameters, and mass, by combining both observational data sets, and by using Monte Carlo models of the observed dust tail. The differential size distribution function that best fits the imaging data was a broken power-law, having a power index of --2.5 for particles of r$\le$ 3 mm, and of --3.7 for larger particles. The particles range in sizes from 1 $\mu$m up to 5 cm. The ejecta is characterized by two components, depending on velocity and ejection direction. The northern component of the double tail, observed since October 8th 2022, might be associated to a secondary ejection event from impacting debris on Didymos, although it is also possible that this feature results from the binary system dynamics alone. The lower limit to the total dust mass ejected is estimated at $\sim$6$\times$10$^6$ kg, half of this mass being ejected to interplanetary space.

Authors:Adam Hibberd

Abstract: The phenomenon of 1I/'Oumuamua introduced the interstellar object (ISO) class of celestial body into the astronomical lexicon, those objects with heliocentric speeds clearly in excess of that required to parabolically escape the Solar System - and therefore of extrasolar origin. A vogue topic at this moment in time is the possibility that some ISOs may impact with Earth, where they would be observed as bolides (meteor fireballs). There is the claim for instance that a meteor listed in the NASA-JPL CNEOS (Center for Near Earth Object Studies) database, CNEOS 2014-01-08 was interstellar, and additionally four further meteors from the database with interstellar origin have been proposed. This paper postulates that the origin of yet another meteor from this catalogue, CNEOS 2017-10-09 (observed over Bolivia, South America), was interstellar, as it may have been associated with 'Oumuamua. Note there is no direct velocity data for this object available, yet its observation time corresponds to the expected arrival time of an object ejected from 'Oumuamua and intersecting Earth's orbital position.

Authors:Elisa Goffo, Davide Gandolfi, Jo Ann Egger, Alexander J. Mustill, Simon H. Albrecht, Teruyuki Hirano, Oleg Kochukhov, Nicola Astudillo-Defru, Oscar Barragan, Luisa M. Serrano, Artie P. Hatzes, Yann Alibert, Eike Guenther, Fei Dai, Kristine W. F. Lam, Szilárd Csizmadia, Alexis M. S. Smith, Luca Fossati, Rafael Luque, Florian Rodler, Mark L. Winther, Jakob L. Rørsted, Javier Alarcon, Xavier Bonfils, William D. Cochran, Hans J. Deeg, Jon M. Jenkins, Judith Korth, John H. Livingston, Annabella Meech, Felipe Murgas, Jaume Orell-Miquel, Hannah L. M. Osborne, Enric Palle, Carina M. Persson, Seth Redfield, George R. Ricker, Sara Seager, Roland Vanderspek, Vincent Van Eylen, Joshua N. Winn

Abstract: GJ 367 is a bright (V $\approx$ 10.2) M1 V star that has been recently found to host a transiting ultra-short period sub-Earth on a 7.7 hr orbit. With the aim of improving the planetary mass and radius and unveiling the inner architecture of the system, we performed an intensive radial velocity follow-up campaign with the HARPS spectrograph -- collecting 371 high-precision measurements over a baseline of nearly 3 years -- and combined our Doppler measurements with new TESS observations from sectors 35 and 36. We found that GJ 367 b has a mass of $M_\mathrm{b}$ = 0.633 $\pm$ 0.050 M$_{\oplus}$ and a radius of $R_\mathrm{b}$ = 0.699 $\pm$ 0.024 R$_{\oplus}$, corresponding to precisions of 8% and 3.4%, respectively. This implies a planetary bulk density of $\rho_\mathrm{b}$ = 10.2 $\pm$ 1.3 g cm$^{-3}$, i.e., 85% higher than Earth's density. We revealed the presence of two additional non transiting low-mass companions with orbital periods of $\sim$11.5 and 34 days and minimum masses of $M_\mathrm{c}\sin{i_\mathrm{c}}$ = 4.13 $\pm$ 0.36 M$_{\oplus}$ and $M_\mathrm{d}\sin{i_\mathrm{d}}$ = 6.03 $\pm$ 0.49 M$_{\oplus}$, respectively, which lie close to the 3:1 mean motion commensurability. GJ 367 b joins the small class of high-density planets, namely the class of super-Mercuries, being the densest ultra-short period small planet known to date. Thanks to our precise mass and radius estimates, we explored the potential internal composition and structure of GJ 367 b, and found that it is expected to have an iron core with a mass fraction of 0.91$^{+0.07}_{-0.23}$. How this iron core is formed and how such a high density is reached is still not clear, and we discuss the possible pathways of formation of such a small ultra-dense planet.

Authors:Khalid Barkaoui, Francisco J. Pozuelos, Coel Hellier, Barry Smalley, Louise D. Nielsen, Caroline Dorn, Prajwal Niraula, Michaël Gillon, Julien de Wit, Ravit Helled, Simon Müller, Emmanuel Jehin, Brice-Olivier Demory, V. Van Grootel, Abderahmane Soubkiou, Mourad Ghachoui, David. R. Anderson, Zouhair Benkhaldoun, Francois Bouchy, Artem Burdanov, Laetitia Delrez, Elsa Ducrot, Lionel Garcia, Abdelhadi Jabiri, Monika Lendl, Pierre F. L. Maxted, Catriona A. Murray, Peter Pihlmann Pedersen, Didier Queloz, Daniel Sebastian, Oliver Turner, Stephane Udry, Mathilde Timmermans, Amaury H. M. J. Triaud, Richard G. West

Abstract: Gas giants transiting bright nearby stars are stepping stones for our understanding of planetary system formation and evolution mechanisms. This paper presents a particularly interesting new specimen of this kind of exoplanet discovered by the WASP-South transit survey, WASP-193b. This planet completes an orbit around its Vmag = 12.2 F9 main-sequence host star every 6.25 d. Our analyses found that WASP-193b has a mass of Mp = 0.139 +/- 0.029 M_Jup and a radius of Rp = 1.464 +/- 0.058 R_ Jup, translating into an extremely low density of rhop = 0.059 +\- 0.014 g/cm^3. The planet was confirmed photometrically by the 0.6-m TRAPPIST-South, the 1.0-m SPECULOOS-South telescopes, and the TESS mission, and spectroscopically by the ESO-3.6-m/HARPS and Euler-1.2-m/CORALIE spectrographs. The combination of its large transit depth (dF~1.4 %), its extremely-low density, its high-equilibrium temperature (Teq = 1254 +/- 31 K), and the infrared brightness of its host star (magnitude Kmag=10.7) makes WASP-193b an exquisite target for characterization by transmission spectroscopy (transmission spectroscopy metric: TSM ~ 600). One single JWST transit observation would yield detailed insights into its atmospheric properties and planetary mass, within ~0.1 dex and ~1% (vs ~20% currently with radial velocity data) respectively.

Authors:D. Turrini, F. Marzari, D. Polychroni, R. Claudi, S. Desidera, D. Mesa, M. Pinamonti, A. Sozzetti, A. Suárez Mascareño, M. Damasso, S. Benatti, L. Malavolta, G. Micela, A. Zinzi, V. J. S. Béjar, K. Biazzo, A. Bignamini, M. Bonavita, F. Borsa, C. del Burgo, G. Chauvin, P. Delorme, J. I. González Hernández, R. Gratton, J. Hagelberg, M. Janson, M. Langlois, A. F. Lanza, C. Lazzoni, N. Lodieu, A. Maggio, L. Mancini, E. Molinari, M. Molinaro, F. Murgas, D. Nardiello

Abstract: Observational data from space and ground-based campaigns reveal that the 10-30 Ma old V1298 Tau star hosts a compact and massive system of four planets. Mass estimates for the two outer giant planets point to unexpectedly high densities for their young ages. We investigate the formation of these two outermost giant planets, V1298 Tau b and e, and the present dynamical state of V1298 Tau's global architecture to shed light on the history of this young and peculiar extrasolar system. We perform detailed N-body simulations to explore the link between the densities of V1298 Tau b and e and their migration and accretion of planetesimals within the native circumstellar disk. We combine N-body simulations and the normalized angular momentum deficit (NAMD) analysis to characterize V1298 Tau's dynamical state and connect it to the formation history of the system. We search for outer planetary companions to constrain V1298 Tau's architecture and the extension of its primordial circumstellar disk. The high densities of V1298 Tau b and e suggest they formed quite distant from their host star, likely beyond the CO$_2$ snowline. The higher nominal density of V1298 Tau e suggests it formed farther out than V1298 Tau b. The current architecture of V1298 Tau is not characterized by resonant chains. Planet-planet scattering with an outer giant planet is the most likely cause for the instability, but our search for outer companions using SPHERE and GAIA observations excludes only the presence of planets more massive than 2 M$_\textrm{J}$. The most plausible scenario for V1298 Tau's formation is that the system is formed by convergent migration and resonant trapping of planets born in a compact and plausibly massive disk. The migration of V1298 Tau b and e leaves in its wake a dynamically excited protoplanetary disk and creates the conditions for the resonant chain breaking by planet-planet scattering.

Authors:Haochang Jiang, Yu Wang, Chris W. Ormel, Sebastiaan Krijt, Ruobing Dong

Abstract: Protoplanetary disks, the birthplaces of planets, commonly feature bright rings and dark gaps in both continuum and line emission maps. Accreting planets are interacting with the disk, not only through gravity, but also by changing the local irradiation and elemental abundances, which are essential ingredients for disk chemistry. We propose that giant planet accretion can leave chemical footprints in the gas local to the planet, which potentially leads to the spatial coincidence of molecular emissions with the planet in ALMA observation. Through 2D multi-fluid hydrodynamical simulations in Athena++ with built-in sublimation, we simulate the process of an accreting planet locally heating up its vicinity, opening a gas gap in the disk, and creating the conditions for C-photochemistry. An accreting planet located outside the methane snowline can render the surrounding gas hot enough to sublimate the C-rich organics off pebbles before they are accreted by the planet. This locally elevates the disk gas-phase C/O ratio, providing a potential explanation for the C$_2$H line-emission rings observed with ALMA. In particular, our findings provide an explanation for the MWC480 disk, where previous work has identified a statistically significant spatial coincidence of line-emission rings inside a continuum gap. Our findings present a novel view of linking the gas accretion of giant planets and their natal disks through the chemistry signals. This model demonstrates that giant planets can actively shape their forming chemical environment, moving beyond the traditional understanding of the direct mapping of primordial disk chemistry onto planets.

Authors:Antonio F. B. A. Prado

Abstract: Gravity-Assisted maneuvers have been used as a technique to reduce fuel consumption in deep space missions for several decades now. It opened the doors of the exterior solar system. The literature shows those results, as well as new versions of this maneuver, which includes: the use of propulsion combined with the close approach, both high or low thrust; the passage by the atmosphere of a planet to help to change the trajectory of the spacecraft; the use of tethers to increase the changes in the velocity of the spacecraft. All those new versions have the goal of increasing the variations of energy given by the maneuver, making possible missions that would not be possible without this technique.

Authors:F. J. T. Salazara, A. F. B. A. Prado

Abstract: To collect additional solar energy during the hours of darkness and to overcome the limited Terrestrial solar power due to the diurnal day night cycle, the concept of a Geostationary Tethered Collecting Solar Power Satellite System has been proposed by several authors in the last years. This tethered system consists of a long tether used to link two bodies: a single large panel with a capability of collecting solar energy, and an Earth-pointing microwave transmitting satellite. In this manner, the solar energy would be collected directly from the space and beamed back down to any point on Earth. Planar configurations, when the panel and the microwave transmitting satellite are placed on geostationary orbits, have been usually investigated to maintain the tethered system around the Earth. However, this configuration implies that the panel and the microwave transmitting satellite must to orbit the Earth in exactly the same orbital plane of all geostationary satellites.

Authors:Silvia Giuliatti Winter, Jadilene Xavier, Antônio Bertachini Prado, Andre Amarante

Abstract: In this work, we present the results of a set of numerical simulations carried out to obtain long-duration orbits for a probe around Titania, Uranus' largest satellite. We also propose orbital maneuvers to extend the lifetime of some orbits. Titania's $J_2$ and $C_{22}$ gravitational coefficients and Uranus' gravitational perturbation are considered. The analysis of lifetime sensitivity due to possible errors in $J_2$ and $C_{22}$ values is investigated using multiple regression models. Simulations were performed for eccentricity equal 10-4, and lifetime maps were constructed. The results show that low-altitude orbits have longer lifetimes due to the balance between the disturbance of Uranus and the gravitational coefficients of Titania. The results also show that non-zero values of periapsis longitude ($\omega$) and ascending node longitude ($\Omega$) are essential to increase lifespan. Furthermore, the results indicate that the most economical maneuver occurs for final orbits of radius equal to 1050 km, this is observed for all inclination values.

Authors:Neil T. Lewis, Nicholas A. Lombardo, Peter L. Read, Juan M. Lora

Abstract: We investigate the characteristics of equatorial waves associated with the maintenance of superrotation in the stratosphere of a Titan general circulation model. A variety of equatorial waves are present in the model atmosphere, including equatorial Kelvin waves, equatorial Rossby waves, and mixed Rossby-gravity waves. In the upper stratosphere, acceleration of superrotation is strongest around solstice and is due to interaction between equatorial Kelvin waves and Rossby-type waves in winter-hemisphere mid-latitudes. The existence of this 'Rossby-Kelvin'-type wave appears to depend on strong meridional shear of the background zonal wind that occurs in the upper stratosphere at times away from the equinoxes. In the lower stratosphere, acceleration of superrotation occurs throughout the year and is partially induced by equatorial Rossby waves, which we speculate are generated by quasigeostrophic barotropic instability. Acceleration of superrotation is generally due to waves with phase speeds close to the zonal velocity of the mean flow. Consequently, they have short vertical wavelengths which are close to the model's vertical grid scale, and therefore are likely to be not properly represented. We suggest this may be a common issue amongst Titan GCMs which should be addressed by future model development.

Authors:J. D. Hartman, G. Á. Bakos, Z. Csubry, A. W. Howard, H. Isaacson, S. Giacalone, A. Chontos, N. Narita, A. Fukui, J. P. de Leon, N. Watanabe, M. Mori, T. Kagetani, I. Fukuda, Y. Kawai, M. Ikoma, E. Palle, F. Murgas, E. Esparza-Borges, H. Parviainen, L. G. Bouma, M. Cointepas, X. Bonfils, J. M. Almenara, Karen A. Collins, Kevin I. Collins, Howard M. Relles, Khalid Barkaoui, Richard P. Schwarz, Ghachoui Mourad, Mathilde Timmermans, Georgina Dransfield, Artem Burdanov, Julien de Wit, Emmanuël Jehin, Amaury H. M. J. Triaud, Michaël Gillon, Zouhair Benkhaldoun, Keith Horne, Ramotholo Sefako, A. Jordán, R. Brahm, V. Suc, Steve B. Howell, E. Furlan, J. E. Schlieder, D. Ciardi, T. Barclay, I. Crossfield, C. D. Dressing, M. Goliguzova, A. Tatarnikov, George R. Ricker, Roland Vanderspek, David W. Latham, S. Seager, Joshua N. Winn, Jon M. Jenkins, Stephanie Striegel, Avi Shporer, Andrew Vanderburg, Alan M. Levine, Veselin B. Kostov, David Watanabe

Abstract: We present the discovery from the TESS mission of two giant planets transiting M dwarf stars: TOI 4201 b and TOI 5344 b. We also provide precise radial velocity measurements and updated system parameters for three other M dwarfs with transiting giant planets: TOI 519, TOI 3629 and TOI 3714. We measure planetary masses of 0.525 +- 0.064 M_J, 0.243 +- 0.020 M_J, 0.689 +- 0.030 M_J, 2.57 +- 0.15 M_J, and 0.412 +- 0.040 M_J for TOI 519 b, TOI 3629 b, TOI 3714 b, TOI 4201 b, and TOI 5344 b, respectively. The corresponding stellar masses are 0.372 +- 0.018 M_s, 0.635 +- 0.032 M_s, 0.522 +- 0.028 M_s, 0.625 +- 0.033 M_s and 0.612 +- 0.034 M_s. All five hosts have super-solar metallicities, providing further support for recent findings that, like for solar-type stars, close-in giant planets are preferentially found around metal-rich M dwarf host stars. Finally, we describe a procedure for accounting for systematic errors in stellar evolution models when those models are included directly in fitting a transiting planet system.

Authors:Megan Delamer, Shubham Kanodia, Caleb I. Cañas, Simon Müller, Ravit Helled, Andrea S. J. Lin, Jessica E. Libby-Roberts, Arvind F. Gupta, Suvrath Mahadevan, Johanna Teske, R. Paul Butler, Samuel W. Yee, Jeffrey D. Crane, Stephen Shectman, David Osip, Yuri Beletsky, Andrew Monson, Jaime A. Alvarado-Montes, Chad F. Bender, Jiayin Dong, Te Han, Joe P. Ninan, Paul Robertson, Arpita Roy, Christian Schwab, Guðmundur Stefánsson, Jason T. Wright

Abstract: We confirm TOI-4201 b as a transiting Jovian mass planet orbiting an early M dwarf discovered by the Transiting Exoplanet Survey Satellite. Using ground based photometry and precise radial velocities from NEID and the Planet Finder Spectrograph, we measure a planet mass of 2.59$^{+0.07}_{-0.06}$ M$_{J}$, making this one of the most massive planets transiting an M-dwarf. The planet is $\sim$0.4\% the mass of its 0.63 M$_{\odot}$ host and may have a heavy element mass comparable to the total dust mass contained in a typical Class II disk. TOI-4201 b stretches our understanding of core-accretion during the protoplanetary phase, and the disk mass budget, necessitating giant planet formation to either take place much earlier in the disk lifetime, or perhaps through alternative mechanisms like gravitational instability.

Authors:Dimitrios Krommydas, Fabio Scardigli

Abstract: In this paper we present phenomenological evidence for the validity of an exponential distance relation (also known as generalized Titius-Bode law) in the 32 planetary systems (31 extra solar plus our Solar System) containing at least 5 planets or more. We produce the semi-log fittings of the data, and we check them against the statistical indicators of $R^2$ and $Median$. Then we compare them with the data of 4000 artificial planetary systems created at random. In this way, a possible origin by chance of the Titius-Bode (TB) law is reasonably ruled out. We also point out that in some systems the fittings can be definitely improved by the insertion of new planets into specific positions. We discuss the Harmonic Resonances method and fittings, and compare them with the Titius-Bode fittings. Moreover, for some specific systems, we compare the TB fitting against a polynomial fitting ($r\sim n^2$). This analysis allows us to conclude that an exponential distance relation can reasonably be considered as ``valid'', or strongly corroborated, also in extra solar planetary systems. Further, it results to be the most economical (in terms of free parameters) and best fitting law for the description of spacing among planetary orbits.

Authors:Miles Timpe, Christian Reinhardt, Thomas Meier, Joachim Stadel, Ben Moore

Abstract: In the leading theory of lunar formation, known as the giant impact hypothesis, a collision between two planet-size objects resulted in a young Earth surrounded by a circumplanetary debris disk from which the Moon later accreted. The range of giant impacts that could conceivably explain the Earth-Moon system is limited by the set of known physical and geochemical constraints. However, while several distinct Moon-forming impact scenarios have been proposed -- from small, high-velocity impactors to low-velocity mergers between equal-mass objects -- none of these scenarios have been successful at explaining the full set of known constraints, especially without invoking controversial post-impact processes. In order to bridge the gap between previous studies and provide a consistent survey of the Moon-forming impact parameter space, we present a systematic study of simulations of potential Moon-forming impacts. In the first paper of this series, we focus on pairwise impacts between non-rotating bodies. Notably, we show that such collisions require a minimum initial angular momentum budget of approximately $2~J_{EM}$ in order to generate a sufficiently massive protolunar disk. We also show that low-velocity impacts ($v_{\infty} \lesssim 0.5~v_{esc}$) with high impactor-to-target mass ratios ($\gamma \to 1$) are preferred to explain the Earth-Moon isotopic similarities. In a follow-up paper, we consider impacts between rotating bodies at various mutual orientations.

Authors:E. A. Meier Valdés, B. M. Morris, B. -O. Demory, A. Brandeker, D. Kitzmann, W. Benz, A. Deline, H. -G. Florén, S. G. Sousa, V. Bourrier, V. Singh, K. Heng, A. Strugarek, D. J. Bower, N. Jäggi, L. Carone, M. Lendl, K. Jones, A. V. Oza, O. D. S. Demangeon, Y. Alibert, R. Alonso, G. Anglada, J. Asquier, T. Bárczy, D. Barrado Navascues, S. C. C. Barros, W. Baumjohann, M. Beck, T. Beck, N. Billot, X. Bonfils, L. Borsato, C. Broeg, J. Cabrera, S. Charnoz, A. Collier Cameron, Sz. Csizmadia, P. E. Cubillos, M. B. Davies, M. Deleuil, L. Delrez, D. Ehrenreich, A. Erikson, A. Fortier, L. Fossati, M. Fridlund, D. Gandolfi, M. Gillon, M. Güdel, M. N. Günther, S. Hoyer, K. G. Isaak, L. L. Kiss, J. Laskar, A. Lecavelier des Etangs, C. Lovis, D. Magrin, P. F. L. Maxted, C. Mordasini, V. Nascimbeni, G. Olofsson, R. Ottensamer, I. Pagano, E. Pallé, G. Peter, G. Piotto, D. Pollacco, D. Queloz, R. Ragazzoni, N. Rando, H. Rauer, I. Ribas, N. C. Santos, M. Sarajlic, G. Scandariato, D. Ségransan, D. Sicilia, A. E. Simon, A. M. S. Smith, M. Steller, Gy. M. Szabó, N. Thomas, S. Udry, B. Ulmer, V. Van Grootel, J. Venturini, N. A. Walton, T. G. Wilson, D. Wolter

Abstract: 55 Cnc e is an ultra-short period super-Earth transiting a Sun-like star. Past observations in the optical range detected a time-variable flux modulation phased with the planetary orbital period whose amplitude is too large to be explained by reflected light and thermal emission alone. The goal of the study is to investigate the origin of the variability and timescale of 55 Cnc e's phase curve modulation. To that end, we used the CHaracterising ExOPlanet Satellite (CHEOPS) whose exquisite photometric precision provides an opportunity to characterise minute changes in the phase curve from orbit to orbit. CHEOPS observed 29 individual visits of 55 Cnc e between March 2020 and February 2022. Based on these observations, we investigate the different processes that could be at the origin of the observed modulation. In particular, we build a toy model to assess whether a circumstellar torus of dust driven by radiation pressure and gravity could match the observed flux variability timescale. We find that 55 Cnc e's phase curve amplitude and peak offset do vary between visits. The sublimation timescales of selected dust species reveal that silicates expected in an Earth-like mantle would not survive long enough to explain the observed phase curve modulation. We find that silicon carbide, quartz and graphite are plausible candidates for the circumstellar torus composition due to their long sublimation timescales. The extensive CHEOPS observations confirm that the phase curve amplitude and offset vary in time. We find that dust could provide the grey opacity source required to match the observations. However, the data at hand do not provide evidence that circumstellar material with variable grain mass per unit area is actually causing the observed variability. Future observations with JWST promise exciting insights on this iconic super-Earth.

Authors:Mariah G. MacDonald, Michael S. Polania Vivas, Skylar D'Angiolillo, Ashley N. Fernandez, Tyler Quinn

Abstract: The study of orbital resonances allows for the constraint of planetary properties of compact systems. We can predict a system's resonances by observing the orbital periods of the planets, as planets in or near mean motion resonance have period ratios that reduce to a ratio of small numbers. However, a period ratio near commensurability does not guarantee a resonance; we must study the system's dynamics and resonant angles to confirm resonance. Because resonances require in-depth study to confirm, and because two-body resonances require a measurement of the eccentricity vector which is quite challenging, very few resonant pairs or chains have been confirmed. We thus remain in the era of small number statistics, not yet able to perform large population synthesis or informatics studies. To address this problem, we build a python package to find, confirm, and analyze mean motion resonances, primarily through N-body simulations. We then analyze all near-resonant planets in the Kepler/K2 and TESS catalogues, confirming over 60 new resonant pairs and various new resonant chains. We additionally demonstrate the package's functionality and potential by characterizing the mass-eccentricity degeneracy of Kepler-80g, exploring the likelihood of an exterior giant planet in Kepler-80, and constraining the masses of planets in Kepler-305. We find that our methods overestimate the libration amplitudes of the resonant angles and struggle to confirm resonances in systems with more than three planets. We identify various systems that are likely resonant chains but that we are unable to confirm, and highlight next steps for exoplanetary resonances.

Authors:Laura Flagg, Jake D. Turner, Emily Deibert, Andrew Ridden-Harper, Ernst de Mooij, Ryan J. MacDonald, Ray Jayawardhana, Neale Gibson, Adam Langeveld, David Sing

Abstract: Exoplanet atmosphere studies are often enriched by synergies with brown dwarf analogs. However, many key molecules commonly seen in brown dwarfs have yet to be confirmed in exoplanet atmospheres. An important example is chromium hydride (CrH), which is often used to probe atmospheric temperatures and classify brown dwarfs into spectral types. Recently, tentative evidence for CrH was reported in the low-resolution transmission spectrum of the hot Jupiter WASP-31b. Here, we present high spectral resolution observations of WASP-31b's transmission spectrum from GRACES/Gemini North and UVES/VLT. We detect CrH at 5.6$\sigma$ confidence, representing the first metal hydride detection in an exoplanet atmosphere at high spectral resolution. Our findings constitute a critical step in understanding the role of metal hydrides in exoplanet atmospheres.

Authors:R. Machado Oliveira, O. C. Winter, R. Sfair, G. Valvano, T. S. Moura, G. Borderes-Motta

Abstract: Didymos and Dimorphos are primary and secondary, respectively, asteroids who compose a binary system that make up the set of Near Earth Asteroids (NEAs). They are targets of the Double Asteroid Redirection Test (DART), the first test mission dedicated to study of planetary defense, for which the main goal is to measure the changes caused after the secondary body is hit by a kinect impactor. The present work intends to conduct a study, through numerical integrations, on the dynamics of massless particles distributed in the vicinity of the two bodies. An approximate shape for the primary body was considered as a model of mass concentrations (mascons) and the secondary was considered as a massive point. Our results show the location and size of stable regions, and also their lifetime.

Authors:Sricharan Balaji, Nihaal Zaveri, Nanae Hayashi, Arcelia Hermosillo Ruiz, Jackson Barnes, Ruth Murray-Clay, Kathryn Volk, Jake Gerhardt, Zain Syed

Abstract: We explore a simplified model of the outcome of an early outer Solar System gravitational upheaval during which objects were captured into Neptune's 3:2 mean motion resonance via scattering rather than smooth planetary migration. We use N-body simulations containing the Sun, the four giant planets, and test particles in the 3:2 resonance to determine whether long-term stability sculpting over 4.5 Gyr can reproduce the observed 3:2 resonant population from an initially randomly scattered 3:2 population. After passing our simulated 3:2 resonant objects through a survey simulator, we find that the semimajor axis (a) and eccentricity (e) distributions are consistent with the observational data (assuming an absolute magnitude distribution constrained by prior studies), suggesting that these could be a result of stability sculpting. However, the inclination (i) distribution cannot be produced be stability sculpting and thus must result from a distinct process that excited the inclinations. Our simulations modestly under-predict the number of objects with high libration amplitudes (A{\phi}), possibly because we do not model transient sticking. Finally, our model under-populates the Kozai subresonance compared to both observations and to smooth migration models. Future work is needed to determine whether smooth migration occurring as Neptune's eccentricity damped to its current value can resolve this discrepancy.

Authors:J. Orell-Miquel, M. Lampón, M. López-Puertas, M. Mallorquín, F. Murgas, A. Peláez-Torres, E. Pallé, E. Esparza-Borge, J. Sanz-Forcada, H. M. Tabernero, L. Nortmann, E. Nagel, H. Parviainen, M. R. Zapatero Osorio, J. A. Caballero, S. Czesla, C. Cifuentes, G. Morello, A. Quirrenbach, P. J. Amado, A. Fernández-Martín, A. Fukui, Th. Henning, K. Kawauchi, J. P. de Leon, K. Molaverdikhani, D. Montes, N. Narita, A. Reiners, I. Ribas, A. Sánchez-López, A. Schweitzer, M. Stangret, F. Yan

Abstract: HD235088 (TOI-1430) is a young star known to host a sub-Neptune-sized planet candidate. We validated the planetary nature of HD235088 b with multiband photometry, refined its planetary parameters, and obtained a new age estimate of the host star, placing it at 600-800 Myr. Previous spectroscopic observations of a single transit detected an excess absorption of He I coincident in time with the planet candidate transit. Here, we confirm the presence of He I in the atmosphere of HD235088 b with one transit observed with CARMENES. We also detected hints of variability in the strength of the helium signal, with an absorption of $-$0.91$\pm$0.11%, which is slightly deeper (2$\sigma$) than the previous measurement. Furthermore, we simulated the He I signal with a spherically symmetric 1D hydrodynamic model, finding that the upper atmosphere of HD235088 b escapes hydrodynamically with a significant mass loss rate of (1.5-5) $\times$10$^{10}$g s$^{-1}$, in a relatively cold outflow, with $T$=3125$\pm$375 K, in the photon-limited escape regime. HD235088 b ($R_{p}$ = 2.045$\pm$0.075 R$_{\oplus}$) is the smallest planet found to date with a solid atmospheric detection - not just of He I but any other atom or molecule. This positions it a benchmark planet for further analyses of evolving young sub-Neptune atmospheres.

Authors:O. Chrenko, R. O. Chametla

Abstract: We investigate the migration of Mars- to super-Earth-sized planets in the vicinity of a pressure bump in a 3D radiative protoplanetary disc while accounting for the effect of accretion heat release. Pressure bumps have often been assumed to act as efficient migration traps, but we show that the situation changes when the thermal forces are taken into account. Our simulations reveal that for planetary masses $\lesssim$$2\,M_{\oplus}$, once their luminosity exceeds the critical value predicted by linear theory, thermal driving causes their orbits to become eccentric, quenching the positive corotation torque responsible for the migration trap. As a result, planets continue migrating inwards past the pressure bump. Additionally, we find that planets that remain circular and evolve in the super-Keplerian region of the bump exhibit a reversed asymmetry of their thermal lobes, with the heating torque having an opposite (negative) sign compared to the standard circular case, thus leading to inward migration as well. We also demonstrate that the super-critical luminosities of planets in question can be reached through the accretion of pebbles accumulating in the bump. Our findings have implications for planet formation scenarios that rely on the existence of migration traps at pressure bumps, as the bumps may repeatedly spawn inward-migrating low-mass embryos rather than harbouring newborn planets until they become massive.

Authors:M. Ghachoui, A. Soubkiou, R. D. Wells, B. V. Rackham, A. H. M. J. Triaud, D. Sebastian, S. Giacalone, K. G. Stassun, D. R. Ciardi, K. A. Collins, A. Liu, Y. Gómez Maqueo Chew, M. Gillon, Z. Benkhaldoun, L. Delrez, J. D. Eastman, O. Demangeon, K. Barkaoui, A. Burdanov, B. -O. Demory, J. de Wit, G. Dransfield, E. Ducrot, L. Garcia, Y. Gómez Maqueo Chew, M. A. Gómez-Muñoz, M. J. Hooton, E. Jehin, C. A. Murray, P. P. Pedersen, F. J. Pozuelos, D. Queloz, L. Sabin, N. Schanche, M. Timmermans, E. J. Gonzales, C. D. Dressing, C. Aganze, A. J. Burgasser, R. Gerasimov, C. Hsu, C. A. Theissen, D. Charbonneau, J. M. Jenkins, D. W. Latham, G. Ricker, S. Seager, A. Shporer, J. D. Twicken, R. Vanderspek, J. N. Winn, K. I. Collins, A. Fukui, T. Gan, N. Narita, R. P. Schwarz

Abstract: We report the discovery by the TESS mission of a super-Earth on a 4.8-d orbit around an inactive M4.5 dwarf (TOI-1680) and its validation with ground-based facilities. The host star is located 37.14 pc away, and it has a radius of 0.2100+/-0.0064 R_sun, a mass of 0.1800+/-0.0044 M_sun and an effective temperature of 3211+/-100 K. We validate and characterize the planet using TESS data, ground-based multi-wavelength photometry from TRAPPIST, SPECULOOS and LCO, and high-resolution AO observations from Keck/NIRC2 and Shane. Our analyses determine the planet to have a radius of 1.466+0.063/-0.049 R_earth and an equilibrium temperature of 404+/-14 K, assuming no albedo and perfect heat redistribution. Assuming a mass based on mass-radius relationships, this planet is a promising target for atmospheric characterization with the James Webb Space Telescope (JWST).

Authors:Adriana Pisarčíková, Pavol Matlovič, Juraj Tóth, Stefan Loehle, Ludovic Ferrière, David Leiser, Felix Grigat, Jérémie Vaubaillon

Abstract: Fragments of small solar system bodies entering Earth's atmosphere have possibly been important contributors of organic compounds to the early Earth. The cyano radical (CN) emission from meteors is considered as potentially one of the most suitable markers of organic compounds in meteoroids, however, its detection in meteor spectra has been thus far unsuccessful. With the aim to improve our abilities to identify CN emission in meteor observations and use its spectral features to characterize the composition of incoming asteroidal meteoroids, we present a detailed analysis of CN emission from high-resolution spectra of 22 laboratory simulated meteors including ordinary, carbonaceous, and enstatite chondrites, as well as a large diversity of achondrites (i.e., ureilite, aubrite, lunar, martian, howardite, eucrite, and diogenite), mesosiderite, and iron meteorites. We describe the variations of CN emission from different classes of asteroidal meteor analogues, its correlation and time evolution relative to other major meteoroid components. We demonstrate that CN can be used as a diagnostic spectral feature of carbonaceous and carbon-rich meteoroids, while most ordinary chondrites show no signs of CN. Our results point out strong correlation between CN and H emission and suggest both volatile features are suitable to trace contents of organic matter and water molecules present within meteoroids. For the application in lower resolution meteor observations, we demonstrate that CN can be best recognized in the early stages of ablation and for carbon-rich materials by measuring relative intensity ratio of CN band peak to the nearby Fe I-4 lines.

Authors:Carsten Güttler, Martin Rose, Holger Sierks, Wolfgang Macher, Stephan Zivithal, Jürgen Blum, Sunny Laddha, Bastian Gundlach, Günter Kargl

Abstract: The diffusion of gas through porous material is important to understand the physical processes underlying cometary activity. We study the diffusion of a rarefied gas (Knudsen regime) through a packed bed of monodisperse spheres via experiments and numerical modelling, providing an absolute value of the diffusion coefficient and compare it to published analytical models. The experiments are designed to be directly comparable to numerical simulations, by using precision steel beads, simple geometries, and a trade-off of the sample size between small boundary effects and efficient computation. For direct comparison, the diffusion coefficient is determined in Direct Simulation Monte Carlo (DSMC) simulations, yielding a good match with experiments. This model is further-on used on a microscopic scale, which cannot be studied in experiments, to determine the mean path of gas molecules and its distribution, and compare it against an analytical model. Scaling with sample properties (particle size, porosity) and gas properties (molecular mass, temperature) is consistent with analytical models. As predicted by these, results are very sensitive on sample porosity and we find that a tortuosity $q(\varepsilon)$ depending linearly on the porosity $\varepsilon$ can well reconcile the analytical model with experiments and simulations. Mean paths of molecules are close to those described in the literature, but their distribution deviates from the expectation for small path lengths. The provided diffusion coefficients and scaling laws are directly applicable to thermophysical models of idealised cometary material.

Authors:Anastasia Consorzi, Daniele Melini, Giorgio Spada

Abstract: Context: Tidal and rotational deformation of fluid giant extra-solar planets may impact their transit light curves, making the $k_2$ Love number observable in the upcoming years. Studying the sensitivity of $k_2$ to mass concentration at depth is thus expected to provide new constraints on the internal structure of gaseous extra-solar planets. Aims: We investigate the link between the mean polar moment of inertia $N$ of a fluid, stably layered extra-solar planet and its $k_2$ Love number, aiming at obtaining analytical relationships valid, at least, for some particular ranges of the model parameters. We also seek a general, approximate relationship useful to constrain $N$ once observations of $k_2$ will become available. Methods: For two-layer fluid extra-solar planets, we explore the relationship between $N$ and $k_2$ by analytical methods, for particular values of the model parameters. We also explore approximate relationships valid over all the possible range of two-layer models. More complex planetary structures are investigated by the semi-analytical propagator technique. Results: A unique relationship between $N$ and $k_2$ cannot be established. However, our numerical experiments show that a `rule of thumb' can be inferred, valid for complex, randomly layered stable planetary structures. The rule robustly defines the upper limit to the values of $N$ for a given $k_2$, and agrees with analytical results for a polytrope of index one and with a realistic non-rotating model of the tidal equilibrium of Jupiter.

Authors:Andrea Banzatti, Klaus M. Pontoppidan, John Carr, Evan Jellison, Ilaria Pascucci, Joan Najita, Carlos E. Munoz-Romero, Karin I. Oberg, Anusha Kalyaan, Paola Pinilla, Sebastiaan Krijt, Feng Long, Michiel Lambrechts, Giovanni Rosotti, Gregory J. Herczeg, Colette Salyk, Ke Zhang, Nick Ballering, Michael R. Meyer, Simon Bruderer, the JDISCS collaboration

Abstract: Previous analyses of mid-infrared water spectra from young protoplanetary disks observed with the Spitzer-IRS found an anti-correlation between water luminosity and the millimeter dust disk radius observed with ALMA. This trend was suggested to be evidence for a fundamental process of inner disk water enrichment, used to explain properties of the Solar System 40 years ago, in which icy pebbles drift inward from the outer disk and sublimate after crossing the snowline. Previous analyses of IRS water spectra, however, were very uncertain due to the low spectral resolution that blended lines together. We present new JWST-MIRI spectra of four disks, two compact and two large with multiple radial gaps, selected to test the scenario that water vapor inside the snowline is regulated by pebble drift. The higher spectral resolving power of MIRI-MRS now yields water spectra that separate individual lines, tracing upper level energies from 900 K to 10,000 K. These spectra clearly reveal excess emission in the low-energy lines in compact disks, compared to the large disks, establishing the presence of a cooler component with $T \approx$ 170-400 K and equivalent emitting radius $R_{\rm{eq}}\approx$ 1-10 au. We interpret the cool water emission as ice sublimation and vapor diffusion near the snowline, suggesting that there is indeed a higher inwards mass flux of icy pebbles in compact disks. Observation of this process opens up multiple exciting prospects to study planet formation chemistry in inner disks with JWST.

Authors:Emily K Pass, Jennifer G Winters, David Charbonneau, Aurelia Balkanski, Nikole Lewis, Maura Lally, Jacob L Bean, Ryan Cloutier, Jason D Eastman

Abstract: Previous studies of the exoplanet LTT 1445Ac concluded that the light curve from the Transiting Exoplanet Survey Satellite (TESS) was consistent with both grazing and non-grazing geometries. As a result, the radius and hence density of the planet remained unknown. To resolve this ambiguity, we observed the LTT 1445 system for six spacecraft orbits of the Hubble Space Telescope (HST) using WFC3/UVIS imaging in spatial scan mode, including one partial transit of LTT 1445Ac. This imaging produces resolved light curves of each of the three stars in the LTT 1445 system. We confirm that the planet transits LTT 1445A and that LTT 1445C is the source of the rotational modulation seen in the TESS light curve, and we refine the estimate of the dilution factor for the TESS data. We perform a joint fit to the TESS and HST observations, finding that the transit of LTT 1445Ac is not grazing with 97% confidence. We measure a planetary radius of 1.10$_{-0.07}^{+0.10}$ R$_\oplus$. Combined with previous radial velocity observations, our analysis yields a planetary mass of $1.36\pm0.19$ M$_\oplus$ and a planetary density of 5.6$_{-1.5}^{+1.7}$ g cm$^{-3}$. LTT 1445Ac is an Earth analog with respect to its mass and radius, albeit with a higher instellation, and is therefore an exciting target for future atmospheric studies.

Authors:Leonardo A. Dos Santos, Antonio García Munõz, David K. Sing, Mercedes López-Morales, Munazza K. Alam, Vincent Bourrier, David Ehrenreich, Gregory W. Henry, Alain Lecavelier des Etangs, Thomas Mikal-Evans, Nikolay K. Nikolov, Jorge Sanz-Forcada, Hannah R. Wakeford

Abstract: One of the most well-studied exoplanets to date, HD 189733 b, stands out as an archetypal hot Jupiter with many observations and theoretical models aimed at characterizing its atmosphere, interior, host star, and environment. We report here on the results of an extensive campaign to observe atmospheric escape signatures in HD 189733 b using the Hubble Space Telescope and its unique ultraviolet capabilities. We have found a tentative, but repeatable in-transit absorption of singly-ionized carbon (C II, $5.2\% \pm 1.4\%$) in the epoch of June-July/2017, as well as a neutral hydrogen (H I) absorption consistent with previous observations. We model the hydrodynamic outflow of HD 189733 b using an isothermal Parker wind formulation to interpret the observations of escaping C and O nuclei at the altitudes probed by our observations. Our forward models indicate that the outflow of HD 189733 b is mostly neutral within an altitude of $\sim 2$ R$_\mathrm{p}$ and singly ionized beyond that point. The measured in-transit absorption of C II at 133.57 nm is consistent with an escape rate of $\sim 1.1 \times 10^{11}$ g$\,$s$^{-1}$, assuming solar C abundance and outflow temperature of $12\,100$ K. Although we find a marginal neutral oxygen (O I) in-transit absorption, our models predict an in-transit depth that is only comparable to the size of measurement uncertainties. A comparison between the observed Lyman-$\alpha$ transit depths and hydrodynamics models suggests that the exosphere of this planet interacts with a stellar wind at least one order of magnitude stronger than solar.

Authors:Assaf Hochman, Thaddeus D. Komacek, Paolo De Luca

Abstract: Humanity is close to characterizing the atmospheres of rocky exoplanets due to the advent of JWST. These astronomical observations motivate us to understand exoplanetary atmospheres to constrain habitability. We study the influence greenhouse gas supplement has on the atmosphere of TRAPPIST-1e, an Earth-like exoplanet, and Earth itself by analyzing ExoCAM and CMIP6 model simulations. We find an analogous relationship between CO2 supplement and amplified warming at non-irradiated regions (night side and polar) - such spatial heterogeneity results in significant global circulation changes. A dynamical systems framework provides additional insight into the vertical dynamics of the atmospheres. Indeed, we demonstrate that adding CO2 increases temporal stability near the surface and decreases stability at low pressures. Although Earth and TRAPPIST-1e take entirely different climate states, they share the relative response between climate dynamics and greenhouse gas supplements.

Authors:Michael Greenberg, Denton S. Ebel

Abstract: The Stardust mission captured comet Wild 2 particles in aerogel at 6.1 km/sec. We performed high resolution three-dimensional imaging and X-ray fluorescence mapping of whole cometary tracks in aerogel. We present the results of a survey of track structures using Laser Scanning Confocal Microscopy, including measurements of track volumes, entry hole size and cross-sectional profiles. We compare various methods for measuring track parameters. We demonstrate a methodology for discerning hypervelocity particle ablation rates using synchrotron-based X-ray fluorescence, combined with mass and volume estimates of original impactors derived from measured track properties. Finally, we present a rough framework for reconstruction of original impactor size, and volume of volatilized material, using our measured parameters. The bulk of this work is in direct support of non-destructive analysis and identification of cometary grains in whole tracks, and its eventual application to the reconstruction of the size, shape, porosity and chemical composition of whole Stardust impactors.

Authors:Herbert Palme, Dominik C. Hezel, Denton S. Ebel

Abstract: One of the major unresolved problems in cosmochemistry is the origin of chondrules, once molten, spherical silicate droplets with diameters of 0.2 to 2 mm. Chondrules are an essential component of primitive meteorites and perhaps of all early solar system materials including the terrestrial planets. Numerous hypotheses have been proposed for their origin. Many carbonaceous chondrites are composed of about equal amounts of chondrules and fine-grained matrix. Recent data confirm that matrix in carbonaceous chondrites has high Si/Mg and Fe/Mg ratios when compared to bulk carbonaceous chondrites with solar abundance ratios. Chondrules have the opposite signature, low Si/Mg and Fe/Mg ratios. In some carbonaceous chondrites chondrules have low Al/Ti ratios, matrix has the opposite signature and the bulk is chondritic. It is shown in detail that these complementary relationships cannot have evolved on the parent asteroid(s) of carbonaceous chondrites. They reflect preaccretionary processes. Both chondrules and matrix must have formed from a single, solar-like reservoir. Consequences of complementarity for chondrule formation models are discussed. An independent origin and/or random mixing of chondrules and matrix can be excluded. Hence, complementarity is a strong constraint for all astrophysical-cosmochemical models of chondrule formation. Although chondrules and matrix formed from a single reservoir, the chondrule-matrix system was open to the addition of oxygen and other gaseous components.

Authors:Jonas M. Schneider, Christoph Burkhardt, Thorsten Kleine

Abstract: Nucleosynthetic isotope anomalies in meteorites allow distinguishing between the non-carbonaceous (NC) and carbonaceous (CC) meteorite reservoirs and show that correlated isotope anomalies exist in both reservoirs. It is debated, however, whether these anomalies reflect thermal processing of presolar dust in the disk or are primordial heterogeneities inherited from the Solar System's parental molecular cloud. Here, using new high-precision 84Sr isotope data, we show that NC meteorites, Mars, and the Earth and Moon are characterized by the same 84Sr isotopic composition. This 84Sr homogeneity of the inner Solar System contrasts with the well-resolved and correlated isotope anomalies among NC meteorites observed for other elements, and most likely reflects correlated s- and (r-, p-)-process heterogeneities leading to 84Sr excess and deficits of similar magnitude which cancel each other. For the same reason there is no clearly resolved 84Sr difference between NC and CC meteorites, because in some carbonaceous chondrites the characteristic 84Sr excess of the CC reservoir is counterbalanced by an 84Sr deficit resulting from s-process variations. Nevertheless, most carbonaceous chondrites exhibit 84Sr excesses, which reflect admixture of refractory inclusions and more pronounced s-process heterogeneities in these samples. Together, the correlated variations of s-, (r-, p-)-process nuclides revealed by the 84Sr data of this study refute an origin of these isotope anomalies solely by processing of presolar dust grains, but points to primordial mixing of isotopically distinct dust reservoirs as the dominant process producing the isotopic heterogeneity of the Solar System.

Authors:Elspeth K. H. Lee

Abstract: Insight into the formation and global distribution of cloud particles in exoplanet atmospheres continues to be a key problem to tackle going into the JWST era. Understanding microphysical cloud processes and atmospheric feedback mechanisms in 3D has proven to be a challenging prospect for exoplaneteers. In an effort to address the large computational burden of coupling these models in 3D simulations, we develop an open source, lightweight and efficient microphysical cloud model for exoplanet atmospheres. `Mini-cloud' is a microphysical based cloud model for exoplanet condensate clouds that can be coupled to contemporary general circulation models (GCMs) and other time dependent simulations. We couple mini-cloud to the Exo-FMS GCM and use a prime JWST target, the hot Jupiter HAT-P-1b, as a test case for the cloud formation module. After 1000+ of days of integration with mini-cloud, our results show a complex 3D cloud structure with cloud properties relating closely the dynamical and temperature properties of the atmosphere. Current transit and emission spectra data are best fit with a reduced cloud particle number density compared to the nominal simulation, with our simulated JWST NIRISS SOSS spectra showing promising prospects for characterising the atmosphere in detail. Overall, our study is another small step in first principles 3D exoplanet cloud formation microphysical modelling. We suggest that additional physics not included in the present model, such as coagulation, are required to reduce the number density of particles to appropriately observed levels.

Authors:Robert D. Kavanagh, Harish K. Vedantham

Abstract: Recent low-frequency radio observations suggest that some nearby M dwarfs could be interacting magnetically with undetected close-in planets, powering the emission via the electron cyclotron maser (ECM) instability. Confirmation of such a scenario could reveal the presence of close-in planets around M dwarfs, which are typically difficult to detect via other methods. ECM emission is beamed, and is generally only visible for brief windows depending on the underlying system geometry. Due to this, detection may be favoured at certain orbital phases, or from systems with specific geometric configurations. In this work, we develop a geometric model to explore these two ideas. Our model produces the visibility of the induced emission as a function of time, based on a set of key parameters that characterise magnetic star-planet interactions. Utilising our model, we find that the orbital phases where emission appears are highly dependent on the underlying parameters, and does not generally appear at the quadrature points in the orbit as is seen for the Jupiter-Io interaction. Then using non-informative priors on the system geometry, we show that untargeted radio surveys are biased towards detecting emission from systems with planets in near face-on orbits. While transiting exoplanets are still likely to be detectable, they are less likely to be seen than those in near face-on orbits. Our forward model serves to be a powerful tool for both interpreting and appropriately scheduling radio observations of exoplanetary systems, as well as inverting the system geometry from observations.

Authors:Lukas Affolter, Christoph Mordasini, Apurva V. Oza, Daria Kubyshkina, Luca Fossati

Abstract: The Kepler satellite has revealed a gap between sub-Neptunes and super-Earths that atmospheric escape models had predicted as an evaporation valley. We seek to contrast results from a simple XUV-driven energy-limited (ELIM) escape model against those from a direct hydrodynamic (HYDRO) model. Besides XUV-driven escape, the latter also includes the boil-off regime. We couple the two models to an internal structure model and follow the planets' temporal evolution over Gyr. To see the population-wide imprint of the two models, we first employ a rectangular grid in initial conditions. We then study the slope of the valley also for initial conditions derived from the Kepler planets. For the rectangular grid, we find that the power-law slope of the valley with respect to orbital period is -0.18 and -0.11 in the ELIM and HYDRO model, respectively. For the initial conditions derived from the Kepler planets, the results are similar (-0.16 and -0.10). While the slope found with the ELIM model is steeper than observed, the one of the HYDRO model is in excellent agreement with observations. The reason for the shallower slope is caused by the two regimes in which the ELIM model fails: First, puffy planets at low stellar irradiation. For them, boil-off dominates mass loss. However, boil-off is absent in the ELIM model, thus it underestimates escape relative to HYDRO. Second, massive compact planets at high XUV irradiation. For them, the ELIM approximation overestimates escape relative to the HYDRO case because of cooling by thermal conduction, neglected in the ELIM model. The two effects act together in concert to yield in the HYDRO model a shallower slope of the valley that agrees very well with observations. We conclude that an escape model that includes boil-off and a more realistic treatment of cooling mechanisms can reproduce one of the most important constraints, the valley slope.

Authors:Dingshan Deng, Maxime Ruaud, Uma Gorti, Ilaria Pascucci

Abstract: CO is one of the most abundant molecules in protoplanetary disks, and optically thin emission from its isotopologues has been detected in many of them. However, several past works have argued that reproducing the relatively low emission of CO isotopologues requires a very low disk mass or significant CO depletion. Here, we present a Python code, DiskMINT, which includes gas density and temperature structures that are both consistent with the thermal pressure gradient, isotope-selective chemistry, and conversion of CO into $\mathrm{CO_2}$ ice on grain-surfaces. The code generates a self-consistent disk structure, where the gas disk distribution is obtained from a Spectral Energy Distribution (SED)-derived dust disk structure with multiple grain sizes. We use DiskMINT to study the disk of RU~Lup, a high-accreting star whose disk was previously inferred to have a gas mass of only $\sim 1.5\times10^{-3}\,M_\odot$ and gas-to-dust mass ratio of $\sim 4$. Our best-fit model to the long-wavelength continuum emission can explain the total $\mathrm{C^{18}O}$ luminosity as well as the $\mathrm{C^{18}O}$ velocity and radial intensity profiles, and obtains a gas mass of $\sim 1.2\times10^{-2}\,M_\odot$, an order of magnitude higher than previous results. A disk model with parametric Gaussian vertical distribution that better matches the IR-SED can also explain the observables above with a similarly high gas mass $\sim 2.1\times10^{-2}\,M_\odot$. We confirm the conclusions of Ruaud et al. (2022) that optically thin $\mathrm{C^{18}O}$ rotational lines provide reasonable estimates of the disk mass and can therefore be used as gas disk tracers.

Authors:Athul Pradeepkumar Girija

Abstract: Aerocapture is a technique which uses atmospheric drag to decelerate a spacecraft and achieve nearly fuel-free orbit insertion from an interplanetary trajectory. The present study performs a historical review of the field, and a bibliometric data analysis of the literature from 1980 to 2023. The data offers insights into the evolution of the field, current state of research, and pathways for its continued development. The data reveal a pattern in the rise of publications, followed by a period of stagnation, which repeats itself approximately once every decade. Mars is the most studied destination, while Uranus is the least studied. Prior to 2013, NASA centers produced the most publications and are the most cited in the field. However, academic institutions produced the majority of publications in the last decade. The United States continues to be the leading country in terms of publications, followed by China. The Journal of Spacecraft and Rockets is the leading source of publications, both in terms of number and citations. NASA is the leading funding source, followed by the National Natural Science Foundation of China. A proposed low-cost Earth flight demonstration of aerocapture will greatly reduce the risk for future science missions.

Authors:Cheongho Han, Chung-Uk Lee, Ian A. Bond, Weicheng Zang, Sun-Ju Chung, Michael D. Albrow, Andrew Gould, Kyu-Ha Hwang, Youn Kil Jung, Yoon-Hyun Ryu, In-Gu Shin, Yossi Shvartzvald, Hongjing Yang, Jennifer C. Yee, Sang-Mok Cha, Doeon Kim, Dong-Jin Kim, Seung-Lee Kim, Dong-Joo Lee, Yongseok Lee, Byeong-Gon Park, Richard W. Pogge, Shude Mao, Wei Zhu, Fumio Abe, Richard Barry, David P. Bennett, Aparna Bhattacharya, Hirosame Fujii, Akihiko Fukui, Ryusei Hamada, Yuki Hirao, Stela Ishitani Silva, Yoshitaka Itow, Rintaro Kirikawa, Iona Kondo, Naoki Koshimoto, Yutaka Matsubara, Shota Miyazaki, Yasushi Muraki, Greg Olmschenk, Clément Ranc, Nicholas J. Rattenbury, Yuki Satoh, Takahiro Sumi, Daisuke Suzuki, Taiga Toda, Mio Tomoyoshi, Paul J. Tristram, Aikaterini Vandorou, Hibiki Yama, Kansuke Yamashita

Abstract: We investigate the microlensing data collected in the 2022 season from the high-cadence microlensing surveys in order to find weak signals produced by planetary companions to lenses. From these searches, we find that two lensing events KMT-2022-BLG-0475 and KMT-2022-BLG-1480 exhibit weak short-term anomalies. From the detailed modeling of the lensing light curves, we identify that the anomalies are produced by planetary companions with a mass ratio to the primary of $q\sim 1.8\times 10^{-4}$ for KMT-2022-BLG-0475L and a ratio $q\sim 4.3\times 10^{-4}$ for KMT-2022-BLG-1480L. It is estimated that the host and planet masses and the projected planet-host separation are $(M_{\rm h}/M_\odot, M_{\rm p}/M_{\rm U}, a_\perp/{\rm au}) = (0.43^{+0.35}_{-0.23}, 1.73^{+1.42}_{-0.92}, 2.03^{+0.25}_{-0.38})$ for KMT-2022-BLG-0475L, and $(0.18^{+0.16}_{-0.09}, 1.82^{+1.60}_{-0.92}, 1.22^{+0.15}_{-0.14})$ for KMT-2022-BLG-1480L, where $M_{\rm U}$ denotes the mass of Uranus. Both planetary systems share common characteristics that the primaries of the lenses are early-mid M dwarfs lying in the Galactic bulge and the companions are ice giants lying beyond the snow lines of the planetary systems.

Authors:C. Richard ICB, V. Boudon ICB, L. Manceron LISA, J. Vander Auwera ULB, SQUARES, S. Vinatier ObsGE, B. Bézard ObsGE, M. Houelle ObsGE

Abstract: We report the measurement of broadening coefficients of pure rotational lines of methane at different pressure and temperature conditions. A total of 27 far-infrared spectra were recorded at the AILES beamline of the SOLEIL synchrotron at room-temperature, 200 K and 120 K, in a range of 10 to 800 mbar. Self and N 2 broadening coefficients and temperature dependence exponents of methane pure rotational lines have been measured in the 73-136 cm --1 spectral range using multi-spectrum non-linear least squares fitting of Voigt profiles. These coefficients were used to model spectra of Titan that were compared to a selection of equatorial Cassini/CIRS spectra, showing a good agreement for a stratospheric methane mole fraction of (1.17 $\pm$ 0.08)%.

Authors:Anina Timmermann, Yutong Shan, Ansgar Reiners, Andreas Pack

Abstract: We introduce ECCOplanets, an open-source Python code that simulates condensation in the protoplanetary disk. Our aim is to analyse how well a simplistic model can reproduce the main characteristics of rocky planet formation. For this purpose, we revisited condensation temperatures ($T_c$) as a means to study disk chemistry, and explored their sensitivity to variations in pressure (p) and elemental abundance pattern. We also examined the bulk compositions of rocky planets around chemically diverse stars. Our T-p-dependent chemical equilibrium model is based on a Gibbs free energy minimisation. We derived condensation temperatures for Solar System parameters with a simulation limited to the most common chemical species. We assessed their change ($\Delta T_c$) as a result of p-variation between $10^{-6}$ and 0.1 bar. To analyse the influence of the abundance pattern, key element ratios were varied, and the results were validated using solar neighbourhood stars. To derive the bulk compositions of planets, we explored three different planetary feeding-zone (FZ) models and compared their output to an external n-body simulation. Our model reproduces the external results well in all tests. For common planet-building elements, we derive a Tc that is within $\pm5$ K of literature values, taking a wider spectrum of components into account. The Tc is sensitive to variations in p and the abundance pattern. For most elements, it rises with p and metallicity. The tested pressure range ($10^{-6} - 0.1$ bar) corresponds to $\Delta T_c \approx +350$ K, and for -0.3 $\leq$ [M/H] $\leq$ 0.4 we find $\Delta T_c \approx +100$ K. An increase in C/O from 0.1 to 0.7 results in a decrease of $\Delta T_c \approx -100$ K. Other element ratios are less influential. Dynamic planetary accretion can be emulated well with any FZ model. Their width can be adapted to reproduce gradual changes in planetary composition.

Authors:Pascal A. Noti, Elspeth K. H. Lee, Russell Deitrick, Mark Hammond

Abstract: Global circulation models (GCMs) play an important role in contemporary investigations of exoplanet atmospheres. Different GCMs evolve various sets of dynamical equations which can result in obtaining different atmospheric properties between models. In this study, we investigate the effect of different dynamical equation sets on the atmospheres of hot Jupiter exoplanets. We compare GCM simulations using the quasi-primitive dynamical equations (QHD) and the deep Navier-Stokes equations (NHD) in the GCM THOR. We utilise a two-stream non-grey "picket-fence" scheme to increase the realism of the radiative transfer calculations. We perform GCM simulations covering a wide parameter range grid of system parameters in the population of exoplanets. Our results show significant differences between simulations with the NHD and QHD equation sets at lower gravity, higher rotation rates or at higher irradiation temperatures. The chosen parameter range shows the relevance of choosing dynamical equation sets dependent on system and planetary properties. Our results show the climate states of hot Jupiters seem to be very diverse, where exceptions to prograde superrotation can often occur. Overall, our study shows the evolution of different climate states which arise just due to different selections of Navier-Stokes equations and approximations. We show the divergent behaviour of approximations used in GCMs for Earth, but applied for non Earth-like planets.

Authors:G. Guilluy, V. Bourrier, Y. Jaziri, W. Dethier, D. Mounzer, P. Giacobbe, O. Attia, R. Allart, A. S. Bonomo, L. A. Dos Santos, M. Rainer, A. Sozzetti

Abstract: The population of close-in exoplanets features a desert of hot Neptunes whose origin is uncertain. These planets may have lost their atmosphere, eroding into mini-Neptunes and super-Earths. Direct observations of evaporating atmospheres are essential to derive mass-loss estimates and constrain this scenario. The metastable 1083.3nm HeI triplet represents a powerful diagnostic of atmospheric evaporation since it traces the hot gas in extended exoplanet atmospheres, is observable from the ground, and is weakly affected by interstellar medium absorption. We conducted a uniform HeI transmission spectroscopy survey, focusing on 9 planets located at the edges of the Neptunian desert, aiming to gain insights into the role of photo-evaporation in its formation. We observed one transit per planet using the high-resolution, near-infrared spectrograph GIANO-B on the Telescopio Nazionale Galileo. We focused our analysis on the HeI triplet by computing high-resolution transmission spectra. We then employed the p-winds model to interpret the observed transmission spectra. We found no sign of planetary absorption in the HeI triplet in any of the investigated targets. We thus provided 3sigma upper-limit estimations on the thermosphere absorption, temperature, and mass loss, and combined them with past measurements to search for correlations with parameters thought to be drivers in the formation of the HeI triplet. Our results strengthen the importance of performing homogeneous surveys and analyses to bring clarification in the HeI detection and hence in the Neptunian desert origin. Our findings corroborate the literature expectations that the HeI absorption signal correlates with the stellar mass and the received XUV flux. However, these trends seem to disappear in terms of mass-loss rates; further studies are essential to shed light on this aspect and to understand better the photo-evaporation process.

Authors:A. Chomez, V. Squicciarini, A. -M. Lagrange, P. Delorme, G. Viswanath, M. Janson, O. Flasseur, G. Chauvin, M. Langlois, P. Rubini, S. Bergeon, D. Albert, M. Bonnefoy, S. Desidera, N. Engler, R. Gratton, T. Henning, E. E. Mamajek, G. -D. Marleau, M. R. Meyer, S. Reffert, S. C. Ringqvist, M. Samland

Abstract: Since 2019, the direct imaging B-star Exoplanet Abundance Study (BEAST) at SPHERE@VLT has been scanning the surroundings of young B-type stars in order to ascertain the ultimate frontiers of giant planet formation. Recently, the $17^{+3}_{-4}$ Myr HIP 81208 was found to host a close-in (~50 au) brown dwarf and a wider (~230 au) late M star around the central 2.6Msun primary. Alongside the continuation of the survey, we are undertaking a complete reanalysis of archival data aimed at improving detection performances so as to uncover additional low-mass companions. We present here a new reduction of the observations of HIP 81208 using PACO ASDI, a recent and powerful algorithm dedicated to processing high-contrast imaging datasets, as well as more classical algorithms and a dedicated PSF-subtraction approach. The combination of different techniques allowed for a reliable extraction of astrometric and photometric parameters. A previously undetected source was recovered at a short separation from the C component of the system. Proper motion analysis provided robust evidence for the gravitational bond of the object to HIP 81208 C. Orbiting C at a distance of ~20 au, this 15Mjup brown dwarf becomes the fourth object of the hierarchical HIP 81208 system. Among the several BEAST stars which are being found to host substellar companions, HIP 81208 stands out as a particularly striking system. As the first stellar binary system with substellar companions around each component ever found by direct imaging, it yields exquisite opportunities for thorough formation and dynamical follow-up studies.

Authors:Raphael Marschall, Alessandro Morbidelli

Abstract: Understanding planetesimal formation is an essential first step to understanding planet formation. The distribution of these first solid bodies will drive the locations where planetary embryos can grow. We seek to understand the parameter space of possible protoplanetary disk formation and evolution models of our Solar System. A good protoplanetary disk scenario for the Solar System must meet at least the following three criteria: 1) an extended dust disk (at least 45 au); 2) formation of planetesimals in at least two distinct locations; and 3) transport of high temperatures condensates (i.e., calcium-aluminium-rich inclusion, CAIs) to the outer disk. We explore a large parameter space to study the effect of the disk viscosity, the timescale of infall of material into the disk, the distance within which material is deposited into the disk, and the fragmentation threshold of dust particles. We find that scenarios with a large initial disk viscosity ($\alpha>0.05$), relatively short infall timescale ($T_{infall}<100-200$ kyr), and a small centrifugal radius ($R_C\sim0.4$~au; the distance within which material falls into the disk) result in disks that satisfy the criteria for a good protoplanetary disk of the Solar System. The large initial viscosity and short infall timescale result in a rapid initial expansion of the disk, which we dub the inflationary phase of the disk. Furthermore, a temperature-dependent fragmentation threshold, which mimics that cold icy particles break more easily, results in larger and more massive disks. This results in more "icy" than "rocky" planetesimals. Such scenarios are also better in line with our Solar System, which has small terrestrial planets and massive giant planet cores. Finally, we find that scenarios with large $R_C$ cannot transport CAIs to the outer disk and do not produce planetesimals at two locations within the disk.

Authors:Joshua B. Lovell, Elliot M. Lynch

Abstract: We present Paper II of the Eccentric Debris Disc Morphologies series to explore the effects that significant free and forced eccentricities have on high-resolution millimetre-wavelength observations of debris discs, motivated by recent ALMA images of HD53143's disc. In this work, we explore the effects of free eccentricity, and by varying disc fractional widths and observational resolutions, show for a range of narrow eccentric discs, orbital overlaps result in dust emission distributions that have either one or two radial peaks at apocentre and/or pericentre. The narrowest discs contain two radial peaks, whereas the broadest discs contain just one radial peak. For fixed eccentricities, as fractional disc widths are increased, we show that these peaks merge first at apocentre (producing apocentre glow), and then at pericentre (producing pericentre glow). Our work thus demonstrates that apocentre/pericentre glows in models with constant free and forced eccentricities can be both width and resolution dependent at millimetre wavelengths, challenging the classical assertion that apocentre/pericentre glows are purely wavelength dependent. We discuss future high-resolution observations that can distinguish between competing interpretations of underlying debris disc eccentricity distributions.

Authors:Avinash S. Nediyedath, Martin J. Fowler, K. Davis, P. Das, D. Lalla, Bryan E. Martin, S. Dixon, P. Lewin, Andre O. Kovacs, A. Odasso, M. Primm, A. Norris

Abstract: NASA citizen scientists from all over the world have used EXOplanet Transit Interpretation Code (EXOTIC) to reduce 71 sets of time-series images of WASP-12 taken by the 6-inch telescope operated by the Centre of Astrophysics | Harvard & Smithsonian MicroObservatory. Of these sets, 24 result in clean Transit light curves of the WASP-12b which are uploaded to the NASA Exoplanet Watch website. We use priors from the NASA Exoplanet Archive to calculate the ephemeris of the planet and combine it with ETD (Exoplanet Transit Database) and ExoClock observations. Combining the Exoplanet Watch, ETD, and Exoclock datasets gives an updated ephemeris for the WASP-12b system of 2454508.97872 +/- 0.00003 with an orbital period of 1.0914196 +/- 1.7325322e-08 days which can be used to inform future space telescope observations.

Authors:Rebecca G. Martin, Philip J. Armitage, Stephen H. Lubow, Daniel J. Price

Abstract: We use numerical simulations of circumplanetary disks to determine the boundary between disks that are radially truncated by the tidal potential, and those where gas escapes the Hill sphere. We consider a model problem, in which a coplanar circumplanetary disk is resupplied with gas at an injection radius smaller than the Hill radius. We evolve the disk using the PHANTOM Smoothed Particle Hydrodynamics code until a steady-state is reached. We find that the most significant dependence of the truncation boundary is on the disk aspect ratio $H/R$. Circumplanetary disks are efficiently truncated for $H/R \lesssim 0.2$. For $H/R \simeq 0.3$, up to about half of the injected mass, depending on the injection radius, flows outwards through the decretion disk and escapes. As expected from analytic arguments, the conditions ($H/R$ and Shakura-Sunyaev $\alpha$) required for tidal truncation are independent of planet mass. A simulation with larger $\alpha=0.1$ shows stronger outflow than one with $\alpha=0.01$, but the dependence on transport efficiency is less important than variations of $H/R$. Our results suggest two distinct classes of circumplanetary disks: tidally truncated thin disks with dust-poor outer regions, and thicker actively decreting disks with enhanced dust-to-gas ratios. Applying our results to the PDS 70c system, we predict a largely truncated circumplanetary disk, but it is possible that enough mass escapes to support an outward flow of dust that could explain the observed disk size.

Authors:Nils B. de Vries, Adrian J. Barker, Rainer Hollerbach

Abstract: Tidal dissipation in star-planet systems can occur through various mechanisms, among which is the elliptical instability. This acts on elliptically deformed equilibrium tidal flows in rotating fluid planets and stars, and excites inertial waves in convective regions if the dimensionless tidal amplitude ($\epsilon$) is sufficiently large. We study its interaction with turbulent convection, and attempt to constrain the contributions of both elliptical instability and convection to tidal dissipation. For this, we perform an extensive suite of Cartesian hydrodynamical simulations of rotating Rayleigh-B\'{e}nard convection in a small patch of a planet. We find that tidal dissipation resulting from the elliptical instability, when it operates, is consistent with $\epsilon^3$, as in prior simulations without convection. Convective motions also act as an effective viscosity on large-scale tidal flows, resulting in continuous tidal dissipation (scaling as $\epsilon^2$). We derive scaling laws for the effective viscosity using (rotating) mixing-length theory, and find that they predict the turbulent quantities found in our simulations very well. In addition, we examine the reduction of the effective viscosity for fast tides, which we observe to scale with tidal frequency ($\omega$) as $\omega^{-2}$. We evaluate our scaling laws using interior models of Hot Jupiters computed with MESA. We conclude that rotation reduces convective length scales, velocities and effective viscosities (though not in the fast tides regime). We estimate that elliptical instability is efficient for the shortest-period Hot Jupiters, and that effective viscosity of turbulent convection is negligible in giant planets compared with inertial waves.

Authors:Tyler Quinn, Mariah MacDonald

Abstract: Although resonant planets have orbital periods near commensurability, resonance is also dictated by other factors, such as the planets' eccentricities and masses, and therefore must be confirmed through a study of the system's dynamics. Here, we perform such a study for five multi-planet systems: Kepler-226, Kepler-254, Kepler-363, Kepler-1542, and K2-32. For each system, we run a suite of N-body simulations that span the full parameter-space that is consistent with the constrained orbital and planetary properties. We study the stability of each system and look for resonances based on the libration of the critical resonant angles. We find strong evidence for a two-body resonance in each system; we confirm a 3:2 resonance between Kepler-226c and Kepler-226d, confirm a 3:2 resonance between Kepler-254c and Kepler-254d, and confirm a three-body 1:2:3 resonant chain between the three planets of Kepler-363. We explore the dynamical history of two of these systems and find that these resonances most likely formed without migration. Migration leads to the libration of the three-body resonant angle, but these angles circulate in both Kepler-254 and Kepler-363. Applying our methods to additional near-resonant systems could help us identify which systems are truly resonant or non-resonant and which systems require additional follow-up analysis.

Authors:Wei Zhu Tsinghua

Abstract: The correlation between close-in super Earths and distant cold Jupiters in planetary systems has important implications for their formation and evolution. In contrary to some earlier findings, a recent study conducted by Bonomo et al.\ suggests that the occurrence of cold Jupiter companions is not excessive in super Earth systems. Here we show that this discrepancy can be seen as a Simpson's paradox and is resolved once the metallicity dependence of the super Earth--cold Jupiter relation is taken into account. A common feature is noticed that almost all the cold Jupiter detections with inner super Earth companions are found around metal-rich stars. Focusing on the Sun-like hosts with super-solar metallicities, we show that the frequency of cold Jupiters conditioned on the presence of inner super Earths is $39_{-11}^{+12}\%$, whereas the frequency of cold Jupiters in the same metallicity range is no more than $20\%$. Therefore, the occurrences of close-in super Earths and distant cold Jupiters appear correlated around metal-rich hosts. The relation between the two types of planets remains unclear for stars with metal-poor hosts due to the limited sample size and the much lower occurrence rate of cold Jupiters, but a correlation between the two cannot be ruled out.

Authors:R. O. Chametla, O. Chrenko, W. Lyra, N. J. Turner

Abstract: We investigate planetary migration in the dead zone of a protoplanetary disk where there are a set of spiral waves propagating inward due to the turbulence in the active zone and the Rossby wave instability (RWI), which occurs at the transition between the dead and active zones. We perform global 3D unstratified magnetohydrodynamical (MHD) simulations of a gaseous disk with the FARGO3D code, using weak gradients in the static resistivity profiles that trigger the formation of a vortex at the outer edge of the dead zone. We find that once the Rossby vortex develops, spiral waves in the dead zone emerge and interact with embedded migrating planets by wave interference, which notably changes their migration. The inward migration becomes faster depending on the mass of the planet, due mostly to the constructive (destructive) interference between the outer (inner) spiral arm of the planet and, the destruction of the dynamics of the horseshoe region by means of the set of background spiral waves propagating inward. The constructive wave interference produces a more negative Lindblad differential torque which inevitably leads to an inward migration. Lastly, for massive planets embedded in the dead zone, we find that the spiral waves can create an asymmetric wider and depeer gap than in the case of $\alpha$-disks, and can prevent the formation of vortices at the outer edge of the gap. The latter could generate a faster or slower migration compared to the standard type-II migration.

Authors:B. Portilla-Revelo, I. Kamp, S. Facchini, E. F. van Dishoeck, C. Law, Ch. Rab, J. Bae, M. Benisty, K. Öberg, R. Teague

Abstract: Embedded planets are potentially the cause of substructures like gaps and cavities observed in several protoplanetary disks. Thus, the substructures observed in the continuum and in line emission encode information about the presence of planets in the system and how they interact with the natal disk. The pre-transitional disk around the star PDS 70 is the first case of two young planets imaged within a dust depleted gap that was likely carved by themselves. We aim to determine the spatial distribution of the gas and dust components in the PDS 70 disk. The axisymmetric substructures observed in the resulting profiles are interpreted in the context of planet-disk interactions. We develop a thermo-chemical forward model for an axisymmetric disk to explain a subset of the Atacama Large Millimeter/Submillimeter Array (ALMA) band 6 observations of three CO isotopologues plus the continuum towards PDS 70. Combining the inferred gas and dust distributions, the model results in a variable gas-to-dust ratio profile throughout the disk that spans two orders of magnitude within the first $130$ au and shows a step gradient towards the outer disk, which is consistent with the presence of a pressure maxima driven by planet-disk interactions. We find a gas density drop factor of ${\sim} 19$ at the location of the planet PDS 70 c with respect to the peak gas density at $75$ au. Combining this value with literature results on the hydrodynamics of planet-disk interactions, we find this gas gap depth to be consistent with independent planet mass estimates from infrared observations. Our findings point towards gas stirring processes taking place in the common gap due to the gravitational perturbation of both planets.

Authors:L. Lange, F. Forget, M. Vincendon, A. Spiga, E. Vos, O. Aharonson, E. Millour, R. Vandemeulebrouck, A. Bierjon

Abstract: Two arguments have suggested the presence of subsurface water ice at latitudes lower than 30\textdegree~on Mars. First, the absence of CO2 frost on pole-facing slopes was explained by the presence of subsurface ice. Second, models suggested that subsurface ice could be stable underneath these slopes. We revisit these arguments with a new slope microclimate model. Our model shows that below 30{\deg} latitude, slopes are warmer than previously estimated as the air above is heated by warm surrounding plains. This additional heat prevents the formation of CO2 and subsurface water ice for most slopes. Higher than 30{\deg}S, our model suggests the presence of subsurface water ice. In sparse cases (steep dusty slopes), subsurface ice may exist down to 25{\deg}S. While hypothetical unstable ice deposits cannot be excluded by our model, our results suggest that water ice is rarer than previously thought in the +- 30{\deg} latitude range considered for human exploration.

Authors:Michael E. Brown, Wesley C. Fraser

Abstract: JWST has shown that CO2 and CO are common on the surfaces of objects in the Kuiper belt and have apparent surface coverages even higher than that of water ice, though water ice is expected to be significantly more abundant in the bulk composition. Using full Mie scattering theory, we show that the high abundance and the unusual spectral behaviour around the 4.26 micron v1 band of CO2 can be explained by a surface covered in a few micron thick layer of ~ 1-2 micron CO2 particles. CO is unstable at the temperatures in the Kuiper belt, so the CO must be trapped in some more stable species. While hydrate clathrates or amorphous water ice are often invoked as a trapping mechanism for outer solar system ices, the expected spectral shift of the absorption line for a CO hydrate clathrates or trapping in amorphous ice is not seen, nor does the H2O abundance appear to be high enough to explain the depth of the CO absorption line. Instead, we suggest that the CO is created via irradiation of CO2 and trapped in the CO2 grains during this process. The presence of a thin surface layer of CO2 with embedded CO suggests volatile differentiation driving CO2 from the interior as a major process driving the surface appearance of these mid-sized Kuiper belt objects, but the mechanisms that control the small grain size and depth of the surface layer remain unclear.

Authors:Yashvir Tiberwal, Nishchal Dwivedi

Abstract: This research paper focuses on the implementation of radial Basis Function (RBF) Support Vector Machines (SVM) for classifying asteroid orbits. Asteroids are important astronomical objects, and their orbits play a crucial role in understanding the dynamics of the solar system. The International Astronomical Union maintains data archives that provide a playground to experiment with various machine-learning techniques. In this study, we explore the application of RBF SVM algorithm to classify asteroids. The results show that the RBF SVM algorithm provides a good efficiency and accuracy to the dataset. We also analyze the impact of various parameters on the performance of the RBF SVM algorithm and present the optimal parameter settings. Our study highlights the importance of using machine learning techniques for classifying asteroid orbits and the effectiveness of the RBF SVM algorithm in this regard.

Authors:Daohai Li, Alexander J. Mustill, Melvyn B. Davies, Yan-Xiang Gong

Abstract: Observations suggested that the occurrence rate of hot Jupiters (HJs) in open clusters is largely consistent with the field ($\sim1\%$) but in the binary-rich cluster M67, the rate is $\sim5\%$. How does the cluster environment boost HJ formation via the high-eccentricity tidal migration initiated by the extreme-amplitude von Zeipel-Lidov-Kozai (XZKL) mechanism forced by a companion star? Our analytical treatment shows that the cluster's collective gravitational potential alters the companion's orbit slowly, which may render the star-planet-companion configuration XZKL-favourable, a phenomenon only possible for very wide binaries. We have also performed direct Gyr $N$-body simulations of the star cluster evolution and XZKL of planets' orbit around member stars. We find that an initially-single star may acquire a companion star via stellar scattering and the companion may enable XZKL in the planets' orbit. Planets around an initially-binary star may also be XZKL-activated by the companion. In both scenarios, the companion's orbit has likely been significantly changed by star scattering and the cluster potential before XZKL occurs in the planets' orbits. Across different cluster models, 0.8\%-3\% of the planets orbiting initially-single stars have experienced XZKL while the fraction is 2\%-26\% for initially-binary stars. Notably, the ejection fraction is similar to or appreciably smaller than XZKL. Around a star that is binary at 1 Gyr, 13\%-32\% of its planets have undergone XZKL, and combined with single stars, the overall XZKL fraction is 3\%-21\%, most affected by the cluster binarity. If 10\% of the stars in M67 host a giant planet, our model predicts an HJ occurrence rate of $\sim1\%$. We suggest that HJ surveys target old, high-binarity, not-too-dense open clusters and prioritise wide binaries to maximise HJ yield.

Authors:Eryn M. Cangi, Michael S. Chaffin, Roger V. Yelle, Bethan S. Gregory, Justin Deighan

Abstract: Although deuterium (D) on Mars has received substantial attention, the deuterated ionosphere remains relatively unstudied. This means that we also know very little about non-thermal D escape from Mars, since it is primarily driven by excess energy imparted to atoms produced in ion-neutral reactions. Most D escape from Mars is expected to be non-thermal, highlighting a gap in our understanding of water loss from Mars. In this work, we set out to fill this knowledge gap. To accomplish our goals, we use an upgraded 1D photochemical model that fully couples ions and neutrals and does not assume photochemical equilibrium. To our knowledge, such a model has not been applied to Mars previously. We model the atmosphere during solar minimum, mean, and maximum, and find that the deuterated ionosphere behaves similarly to the H-bearing ionosphere, but that non-thermal escape on the order of 8000-9000 cm$^{-2}$s$^{-1}$ dominates atomic D loss under all solar conditions. The total fractionation factor, $f$, is $f=0.04$--0.07, and integrated water loss is 147--158 m GEL. This is still less than geomorphological estimates. Deuterated ions at Mars are likely difficult to measure with current techniques due to low densities and mass degeneracies with more abundant H ions. Future missions wishing to measure the deuterated ionosphere in situ will need to develop innovative techniques to do so.

Authors:Nagayoshi Ohashi Insa Choi, John J. Tobin Insa Choi, Jes K. Jørgensen Insa Choi, Shigehisa Takakuwa Insa Choi, Patrick Sheehan Insa Choi, Yuri Aikawa Insa Choi, Zhi-Yun Li Insa Choi, Leslie W. Looney Insa Choi, Jonathan P. Willians Insa Choi, Yusuke Aso Insa Choi, Rajeeb Sharma Insa Choi, Jinshi Sai Insa Choi, Yoshihide Yamato, Jeong-Eun Lee, Kengo Tomida, Hsi-Wei Yen, Frankie J Encalada, Christian Flores, Sacha Gavino, Miyu Kido, Ilseung Han, Zhe-Yu Daniel Lin, Suchitra Narayanan, Nguyen Thi Phuong, Alejandro Santamaría-Miranda, Travis J. Thieme, Merel L. R. van 't Hoff, Itziar de Gregorio-Monsalvo, Patrick M. Koch, Woojin Kwon, Shih-Ping Lai, Chang Won Lee, Adele Plunkett, Kazuya Saigo, Shingo Hirano, Ka Ho Lam, Shoji Mori

Abstract: We present an overview of the Large Program, ``Early Planet Formation in Embedded Disks (eDisk)'', conducted with the Atacama Large Millimeter/submillimeter Array (ALMA). The ubiquitous detections of substructures, particularly rings and gaps, in protoplanetary disks around T Tauri stars raise the possibility that at least some planet formation may have already started during the embedded stages of star formation. In order to address exactly how and when planet formation is initiated, the program focuses on searching for substructures in disks around 12 Class 0 and 7 Class I protostars in nearby ($< $200 pc) star-forming regions through 1.3 mm continuum observations at a resolution of $\sim7$ au (0.04"). The initial results show that the continuum emission, mostly arising from dust disks around the sample protostars, has relatively few distinctive substructures, such as rings and spirals, in marked contrast to Class II disks. The dramatic difference may suggest that substructures quickly develop in disks when the systems evolve from protostars to Class II sources or alternatively that high optical depth of the continuum emission could obscure internal structures. Kinematic information obtained through CO isotopologue lines and other lines reveals the presence of Keplerian disks around protostars, providing us with crucial physical parameters, in particular, the dynamical mass of the central protostars. We describe the background of the eDisk program, the sample selection and their ALMA observations, the data reduction, and also highlight representative first-look results.

Authors:Merel L. R. van 't Hoff Insa Choi, John J. Tobin Insa Choi, Zhi-Yun Li Insa Choi, Nagayoshi Ohashi Insa Choi, Jes K. Jørgensen Insa Choi, Zhe-Yu Daniel Lin Insa Choi, Yuri Aikawa Insa Choi, Yusuke Aso Insa Choi, Itziar de Gregorio-Monsalvo Insa Choi, Sacha Gavino Insa Choi, Ilseung Han Insa Choi, Patrick M. Koch Insa Choi, Woojin Kwon Insa Choi, Chang Won Lee Insa Choi, Jeong-Eun Lee Insa Choi, Leslie W. Looney Insa Choi, Suchitra Narayanan Insa Choi, Adele Plunkett Insa Choi, Jinshi Sai Insa Choi, Alejandro Santamaría-Miranda, Rajeeb Sharma, Patrick D. Sheehan, Shigehisa Takakuwa, Travis J. Thieme, Jonathan P. Williams, Shih-Ping Lai, Nguyen Thi Phuong, Hsi-Wei Yen

Abstract: Studying the physical and chemical conditions of young embedded disks is crucial to constrain the initial conditions for planet formation. Here, we present Atacama Large Millimeter/submillimeter Array (ALMA) observations of dust continuum at $\sim$0.06" (8 au) resolution and molecular line emission at $\sim$0.17" (24 au) resolution toward the Class 0 protostar L1527 IRS from the Large Program eDisk (Early Planet Formation in Embedded Disks). The continuum emission is smooth without substructures, but asymmetric along both the major and minor axes of the disk as previously observed. The detected lines of $^{12}$CO, $^{13}$CO, C$^{18}$O, H$_2$CO, c-C$_3$H$_2$, SO, SiO, and DCN trace different components of the protostellar system, with a disk wind potentially visible in $^{12}$CO. The $^{13}$CO brightness temperature and the H$_2$CO line ratio confirm that the disk is too warm for CO freeze out, with the snowline located at $\sim$350 au in the envelope. Both molecules show potential evidence of a temperature increase around the disk-envelope interface. SO seems to originate predominantly in UV-irradiated regions such as the disk surface and the outflow cavity walls rather than at the disk-envelope interface as previously suggested. Finally, the continuum asymmetry along the minor axis is consistent with the inclination derived from the large-scale (100" or 14,000 au) outflow, but opposite to that based on the molecular jet and envelope emission, suggesting a misalignment in the system. Overall, these results highlight the importance of observing multiple molecular species in multiple transitions to characterize the physical and chemical environment of young disks.

Authors:Yoshihide Yamato Insa Choi, Yuri Aikawa Insa Choi, Nagayoshi Ohashi Insa Choi, John J. Tobin Insa Choi, Jes K. Jørgensen Insa Choi, Shigehisa Takakuwa Insa Choi, Yusuke Aso Insa Choi, Jinshi Sai Insa Choi, Christian Flores, Itziar de Gregorio-Monsalvo, Shingo Hirano, Ilseung Han, Miyu Kido, Patrick M. Koch, Woojin Kwon, Shih-Ping Lai, Chang Won Lee, Jeong-Eun Lee, Zhi-Yun Li, Zhe-Yu Daniel Lin, Leslie W. Looney, Shoji Mori, Suchitra Narayanan, Nguyen Thi Phuong, Kazuya Saigo, Alejandro Santamaría-Miranda, Rajeeb Sharma, Travis J. Thieme, Kengo Tomida, Merel L. R. van 't Hoff, Hsi-Wei Yen

Abstract: Constraining the physical and chemical structure of young embedded disks is crucial to understanding the earliest stages of planet formation. As part of the Early Planet Formation in Embedded Disks Atacama Large Millimeter/submillimeter Array Large Program, we present high spatial resolution ($\sim$0$.\!\!^{\prime\prime}$1 or $\sim$15 au) observations of the 1.3 mm continuum and $^{13}$CO $J=$ 2-1, C$^{18}$O $J=$ 2-1, and SO $J_N=$ $6_5$-$5_4$ molecular lines toward the disk around the Class I protostar L1489 IRS. The continuum emission shows a ring-like structure at 56 au from the central protostar and a tenuous, optically thin emission extending beyond $\sim$300 au. The $^{13}$CO emission traces the warm disk surface, while the C$^{18}$O emission originates from near the disk midplane. The coincidence of the radial emission peak of C$^{18}$O with the dust ring may indicate a gap-ring structure in the gaseous disk as well. The SO emission shows a highly complex distribution, including a compact, prominent component at $\lesssim$30 au, which is likely to originate from thermally sublimated SO molecules. The compact SO emission also shows a velocity gradient along a slightly ($\sim15^\circ$) tilted direction with respect to the major axis of the dust disk, which we interpret as an inner warped disk in addition to the warp around $\sim$200 au suggested by previous work. These warped structures may be formed by a planet or companion with an inclined orbit, or by a gradual change in the angular momentum axis during gas infall.

Authors:Zhe-Yu Daniel Lin Insa Choi, Zhi-Yun Li Insa Choi, John J. Tobin Insa Choi, Nagayoshi Ohashi Insa Choi, Jes Kristian Jørgensen Insa Choi, Leslie W. Looney Insa Choi, Yusuke Aso Insa Choi, Shigehisa Takakuwa Insa Choi, Yuri Aikawa Insa Choi, Merel L. R. van 't Hoff Insa Choi, Itziar de Gregorio-Monsalvo Insa Choi, Frankie J. Encalada Insa Choi, Christian Flores Insa Choi, Sacha Gavino Insa Choi, Ilseung Han Insa Choi, Miyu Kido Insa Choi, Patrick M. Koch Insa Choi, Woojin Kwon Insa Choi, Shih-Ping Lai Insa Choi, Chang Won Lee Insa Choi, Jeong-Eun Lee Insa Choi, Nguyen Thi Phuong Insa Choi, Jinshi Sai Insa Choi, Rajeeb Sharma, Patrick Sheehan, Travis J. Thieme, Jonathan P. Williams, Yoshihide Yamato, Hsi-Wei Yen

Abstract: While dust disks around optically visible, Class II protostars are found to be vertically thin, when and how dust settles to the midplane are unclear. As part of the Atacama Large Millimeter/submillimeter Array (ALMA) large program, Early Planet Formation in Embedded Disks, we analyze the edge-on, embedded, Class I protostar IRAS 04302+2247, also nicknamed the ``Butterfly Star." With a resolution of 0.05" (8~au), the 1.3 mm continuum shows an asymmetry along the minor axis which is evidence of an optically thick and geometrically thick disk viewed nearly edge-on. There is no evidence of rings and gaps, which could be due to the lack of radial substructure or the highly inclined and optically thick view. With 0.1" (16~au) resolution, we resolve the 2D snow surfaces, i.e., the boundary region between freeze-out and sublimation, for $^{12}$CO $J$=2--1, $^{13}$CO $J$=2--1, C$^{18}$O $J$=2--1, $H_{2}$CO $J$=$3_{0,3}$--$2_{0,2}$, and SO $J$=$6_{5}$--$5_{4}$, and constrain the CO midplane snow line to $\sim 130$ au. We find Keplerian rotation around a protostar of $1.6 \pm 0.4 M_{\odot}$ using C$^{18}$O. Through forward ray-tracing using RADMC-3D, we find that the dust scale height is $\sim 6$ au at a radius of 100~au from the central star and is comparable to the gas pressure scale height. The results suggest that the dust of this Class~I source has yet to vertically settle significantly.

Authors:Miyu Kido Insa Choi, Shigehisa Takakuwa Insa Choi, Kazuya Saigo Insa Choi, Nagayoshi Ohashi Insa Choi, John J. Tobin Insa Choi, Jes K Insa Choi, Jørgensen Insa Choi, Yuri Aikawa Insa Choi, Yusuke Aso Insa Choi, Frankie J. Encalada Insa Choi, Christian Flores Insa Choi, Sacha Gavino Insa Choi, Itziar de Gregorio-Monsalvo Insa Choi, Ilseung Han Insa Choi, Shingo Hirano Insa Choi, Patrick M. Koch Insa Choi, Woojin Kwon Insa Choi, Shih-Ping Lai Insa Choi, Chang Won Lee Insa Choi, Jeong-Eun Lee Insa Choi, Zhi-Yun Li Insa Choi, Zhe-Yu Daniel Lin Insa Choi, Leslie W. Looney Insa Choi, Shoji Mori Insa Choi, Suchitra Narayanan Insa Choi, Adele L. Plunkett Insa Choi, Nguyen Thi Phuong Insa Choi, Jinshi Sai Insa Choi, Alejandro Santamarîa-Miranda, Rajeeb Sharma, Patrick Sheehan, Travis J. Thieme, Kengo Tomida, Merel L. R. van't Hoff, Jonathan P. Williams, Yoshihide Yamato, Hsi-Wei Yen

Abstract: We present observations of the Class 0 protostar IRAS 16544-1604 in CB 68 from the ''Early Planet Formation in Embedded Disks (eDisk)'' ALMA Large program. The ALMA observations target continuum and lines at 1.3-mm with an angular resolution of $\sim$5 au. The continuum image reveals a dusty protostellar disk with a radius of $\sim$30 au seen close to edge-on, and asymmetric structures both along the major and minor axes. While the asymmetry along the minor axis can be interpreted as the effect of the dust flaring, the asymmetry along the major axis comes from a real non-axisymmetric structure. The C$^{18}$O image cubes clearly show the gas in the disk that follows a Keplerian rotation pattern around a $\sim$0.14 $M_{\odot}$ central protostar. Furthermore, there are $\sim$1500 au-scale streamer-like features of gas connecting from North-East, North-North-West, and North-West to the disk, as well as the bending outflow as seen in the $^{12}$CO (2-1) emission. At the apparent landing point of NE streamer, there are SO (6$_5$-5$_4$) and SiO (5-4) emission detected. The spatial and velocity structure of NE streamer can be interpreted as a free-falling gas with a conserved specific angular momentum, and the detection of the SO and SiO emission at the tip of the streamer implies presence of accretion shocks. Our eDisk observations have unveiled that the Class 0 protostar in CB 68 has a Keplerian rotating disk with flaring and non-axisymmetric structure associated with accretion streamers and outflows.

Authors:Jin Beniyama, Shigeyuki Sako, Katsuhito Ohtsuka, Tomohiko Sekiguchi, Masateru Ishiguro, Daisuke Kuroda, Seitaro Urakawa, Fumi Yoshida, Asami Takumi, Natsuho Maeda, Jun Takahashi, Seiko Takagi, Hiroaki Saito, Tatsuya Nakaoka, Tomoki Saito, Tomohiro Ohshima, Ryo Imazawa, Masato Kagitani, Satoshi Takita

Abstract: Asteroid systems such as binaries and pairs are indicative of physical properties and dynamical histories of the Small Solar System Bodies. Although numerous observational and theoretical studies have been carried out, the formation mechanism of asteroid pairs is still unclear, especially for near-Earth asteroid (NEA) pairs. We conducted a series of optical photometric and polarimetric observations of a small NEA 2010 XC$_{15}$ in 2022 December to investigate its surface properties. The rotation period of 2010 XC$_{15}$ is possibly a few to several dozen hours and color indices of 2010 XC$_{15}$ are derived as $g-r=0.435\pm0.008$, $r-i=0.158\pm0.017$, and $r-z=0.186\pm0.009$ in the Pan-STARRS system. The linear polarization degrees of 2010 XC$_{15}$ are a few percent at the phase angle range of 58$^{\circ}$ to 114$^{\circ}$. We found that 2010 XC$_{15}$ is a rare E-type NEA on the basis of its photometric and polarimetric properties. Taking the similarity of not only physical properties but also dynamical integrals and the rarity of E-type NEAs into account, we suppose that 2010 XC$_{15}$ and 1998 WT$_{24}$ are of common origin (i.e., asteroid pair). These two NEAs are the sixth NEA pair and first E-type NEA pair ever confirmed, possibly formed by rotational fission. We conjecture that the parent body of 2010 XC$_{15}$ and 1998 WT$_{24}$ was transported from the main-belt through the $\nu_6$ resonance or Hungaria region.

Authors:Xinyan Hua, Sharon Xuesong Wang, Johanna K. Teske, Tianjun Gan, Avi Shporer, George Zhou, Keivan G. Stassun, Markus Rabus, Steve B. Howell, Carl Ziegler, Jack J. Lissauer, Joshua N. Winn, Jon M. Jenkins, Eric B. Ting, Karen A. Collins, Andrew W. Mann, Wei Zhu, Su Wang, R. Paul Butler, Jeffrey D. Crane, Stephen A. Shectman, Luke G. Bouma, Cesar Briceno, Diana Dragomir, William Fong, Nicholas Law, Jennifer V. Medina, Samuel N. Quinn, George R. Ricker, Richard P. Schwarz, Sara Seager, Ramotholo Sefako, Chris Stockdale, Roland Vanderspek, Joel Villasenor

Abstract: We report the confirmation of a TESS-discovered transiting super-Earth planet orbiting a mid-G star, HD 307842 (TOI-784). The planet has a period of 2.8 days, and the radial velocity (RV) measurements constrain the mass to be 9.67+0.83/-0.82 [Earth Masses]. We also report the discovery of an additional planet candidate on an outer orbit that is most likely non-transiting. The possible periods of the planet candidate are approximately 20 to 63 days, with the corresponding RV semi-amplitudes expected to range from 3.2 to 5.4 m/s and minimum masses from 12.6 to 31.1 [Earth Masses]. The radius of the transiting planet (planet b) is 1.93+0.11/-0.09 [Earth Radii], which results in a mean density of 7.4+1.4/-1.2 g/cm^3 suggesting that TOI-784b is likely to be a rocky planet though it has a comparable radius to a sub-Neptune. We found TOI-784b is located at the lower edge of the so-called ``radius valley'' in the radius vs. insolation plane, which is consistent with the photoevaporation or core-powered mass loss prediction. The TESS data did not reveal any significant transit signal of the planet candidate, and our analysis shows that the orbital inclinations of planet b and the planet candidate are 88.60+0.84/-0.86 degrees and <= 88.3-89.2 degrees, respectively. More RV observations are needed to determine the period and mass of the second object, and search for additional planets in this system.

Authors:Ravit Helled

Abstract: The formation history of giant planets inside and outside the solar system remains unknown. We suggest that runaway gas accretion is initiated only at a mass of ~100 M_Earth and that this mass corresponds to the transition to a gas giant, a planet that its composition is dominated in hydrogen and helium. Delaying runaway accretion to later times (a few Myr) and higher masses is likely to be a result of an intermediate stage of efficient heavy-element accretion (at a rate of ~10^-5 M_Earth/yr) that provides sufficient energy to hinder rapid gas accretion. This may imply that Saturn has never reached runaway gas accretion, and that it is a "failed giant planet". The transition to a gas giant planet above Saturn's mass naturally explains the differences between the bulk metallicities and internal structures of Jupiter and Saturn. The transition mass to a gas giant planets strongly depends on the exact formation history and birth environment of the planets, which are still not well constrained for our Solar System. In terms of giant exoplanets, delaying runaway gas accretion to planets beyond Saturn's mass can explain the transitions in the mass-radius relations of observed exoplanets and the high metallicity of intermediate-mass exoplanets.

Authors:K. Yumoto, E. Tatsumi, T. Kouyama, D. R. Golish, S. Kameda, H. Sato, B. Rizk, D. N. DellaGiustina, Y. Yokota, H. Suzuki, J. de León, H. Campins, J. Licandro, M. Popescu, J. L. Rizos, R. Honda, M. Yamada, T. Morota, N. Sakatani, Y. Cho, C. Honda, M. Matsuoka, M. Hayakawa, H. Sawada, K. Ogawa, Y. Yamamoto, S. Sugita, D. S. Lauretta

Abstract: Proximity observations of (162173) Ryugu by the telescopic Optical Navigation Camera onboard Hayabusa2 and (101955) Bennu by MapCam onboard Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer found opposite spectral trends of space weathering on these carbonaceous asteroids. Whether the space weathering trends on these asteroids evolved from the same starting spectra would place an important constraint for understanding their relation. However, systematic error between data obtained by the two imagers needed to be reduced for accurate comparison. To resolve this problem, we cross calibrated albedo and color data using the Moon as the common standard. We show that the cross-calibrated reflectance can be obtained by upscaling the pre-cross-calibrated reflectance of Bennu by 12 +/- 2% at v-band, reducing the systematic errors down to 2%. The cross-calibrated data show that Bennu is brighter by 16 +/- 2% at v-band and bluer in spectral slope by 0.19 +/- 0.05 (/um) than Ryugu. The spectra of fresh craters on Ryugu and Bennu before cross calibration appeared to follow two parallel trend lines with offset, but they converged to a single trend after cross calibration. Such a post-cross-calibration perspective raise the possibility that Ryugu and Bennu evolved from materials with similar visible spectra but evolved in diverging directions by space weathering. The divergent evolution can be caused by the difference in space weathering dose/process and/or composition of the starting material. Thus, comparing the composition of samples returned from Ryugu and Bennu may change the way we interpret the spectral variation of C-complex asteroids.

Authors:Ariane Courtot, Melaine Saillenfest, Jérémie Vaubaillon, Marc Fouchard

Abstract: Context. Dynamically linking a meteor shower with its parent body is challenging, and chaos in the dynamics of meteoroid streams may be one of the reasons. For a robust identification of parent bodies, it is therefore necessary to quantify the amount of chaos involved in the evolution of meteoroid streams. Aims. The characterisation of chaos in meteoroid streams thanks to chaos maps is still a new field of study. We aim to study two very different meteoroid streams, the Draconids and the Leonids, in order to obtain a general view of this topic. Methods. We use the method developed in a previous paper dedicated to Geminids, drawing chaos maps with the orthogonal fast Lyapunov indicator. We choose four particle size ranges to investigate the effect of non-gravitational forces. As the dynamics is structured by mean-motion resonances with planets, we compute the locations and widths of the resonances at play. We use semi-analytical formulas valid for any eccentricity and inclination and an arbitrary number of planets. Results. We pinpoint which mean-motion resonances with Jupiter play a major role in the dynamics of each meteoroid stream. We show how those resonances tend to trap mostly large particles, preventing them from meeting with Jupiter. We also study particles managing to escape those resonances, thanks to the gravitational perturbation of Saturn for example. Finally, we explain why non-gravitational forces do not disturb the dynamics much, contrary to what is observed for the Geminids.

Authors:Billy Edwards, Quentin Changeat, Angelos Tsiaras, Andrew Allan, Patrick Behr, Simone R. Hagey, Michael D. Himes, Sushuang Ma, Keivan G. Stassun, Luis Thomas, Alexandra Thompson, Aaron Boley, Luke Booth, Jeroen Bouwman, Kevin France, Nataliea Lowson, Annabella Meech, Caprice L. Phillips, Aline A. Vidotto, Kai Hou Yip, Michelle Bieger, Amelie Gressier, Estelle Janin, Ing-Guey Jiang, Pietro Leonardi, Subhajit Sarkar, Nour Skaf, Jake Taylor, Ming Yang, Derek Ward-Thompson

Abstract: We present an atmospheric analysis of LTT 9779 b, a rare planet situated in the hot Neptune desert, that has been observed with HST WFC3 G102 and G141. The combined transmission spectrum, which covers 0.8 - 1.6 $\mu$m, shows a gradual increase in transit depth with wavelength. Our preferred atmospheric model shows evidence for H$_{\rm 2}$O, CO$_{\rm 2}$ and FeH with a significance of 3.1 $\sigma$, 2.4 $\sigma$ and 2.1 $\sigma$, respectively. In an attempt to constrain the rate of atmospheric escape for this planet, we search for the 1.083 $\mu$m Helium line in the G102 data but find no evidence of excess absorption that would indicate an escaping atmosphere using this tracer. We refine the orbital ephemerides of LTT 9779 b using our HST data and observations from TESS, searching for evidence of orbital decay or apsidal precession, which is not found. The phase-curve observation of LTT 9779 b with JWST NIRISS should provide deeper insights into the atmosphere of this planet and the expected atmospheric escape might be detected with further observations concentrated on other tracers such as Lyman $\alpha$.

Authors:Matthew Beaudoin, Brett Gladman, Yukun Huang, Michele Bannister, J. J. Kavelaars, Jean-Marc Petit, Kathryn Volk

Abstract: The detached transneptunian objects (TNOs) are those with semimajor axes beyond the 2:1 resonance with Neptune, which are neither resonant nor scattering. Using the detached sample from the OSSOS telescopic survey, we produce the first studies of their orbital distribution based on matching the orbits and numbers of the known TNOs after accounting for survey biases. We show that the detached TNO perihelion ($q$) distribution cannot be uniform, but is instead better matched by two uniform components with a break near $q\approx40$ au. We produce parametric two-component models that are not rejectable by the OSSOS data set, and estimate that there are $36,\!000^{+12,000}_{-9,000}$ detached TNOs with absolute magnitudes $H_r < 8.66$ ($D \gtrsim 100$ km) and semimajor axes $48 < a < 250$ au (95% confidence limits). Although we believe these heuristic two-parameter models yield a correct population estimate, we then use the same methods to show that the perihelion distribution of a detached disk created by a simulated rogue planet matches the $q$ distribution even better, suggesting that the temporary presence of other planets in the early Solar System is a promising model to create today's large semimajor axis TNO population. This numerical model results in a detached TNO population estimate of $48,\!000^{+15,000}_{-12,000}$. Because this illustrates how difficult-to-detect $q>50$ au objects are likely present, we conclude that there are $(5 \pm 2)\times10^4$ dynamically detached TNOs, which are thus roughly twice as numerous as the entire transneptunian hot main belt.

Authors:Bhavesh Jaiswal, Tyler D. Robinson

Abstract: The presence of aerosols in an exoplanet atmosphere can veil the underlying material and can lead to a flat transmission spectrum during primary transit observations. In this work, we explore forward scattering effects from super-micron sized aerosol particles present in the atmosphere of a transiting exoplanet. We find that the impacts of forward scattering from larger aerosols can significantly impact exoplanet transits and the strength of these effects can be dependent on wavelength. In certain cloud configurations, the forward-scattered light can effectively pass through the clouds unhindered, thus rendering the clouds transparent. The dependence of the aerosol scattering properties on wavelength can then lead to a positive slope in the transit spectrum. These slopes are characteristically different from both Rayleigh and aerosol absorption slopes. As examples, we demonstrate scattering effects for both a rocky world and a hot Jupiter. In these models, the predicted spectral slopes due to forward scattering effects can manifest in the transit spectrum at the level of $\sim$10s to $\sim$100s of parts per million and, hence, could be observable with NASA's James Webb Space Telescope.

Authors:P. Stephenson, A. Beth, J. Deca, M. Galand, C. Goetz, P. Henri, K. Heritier, Z. Lewis, A. Moeslinger, H. Nilsson, M. Rubin

Abstract: We examine the origin of electrons in a weakly outgassing comet, using Rosetta mission data and a 3D collisional model of electrons at a comet. We have calculated a new dataset of electron-impact ionization (EII) frequency throughout the Rosetta escort phase, with measurements of the Rosetta Plasma Consortium's Ion and Electron Sensor (RPC/IES). The EII frequency is evaluated in 15-minute intervals and compared to other Rosetta datasets. Electron-impact ionization is the dominant source of electrons at 67P away from perihelion and is highly variable (by up to three orders of magnitude). Around perihelion, EII is much less variable and less efficient than photoionization at Rosetta. Several drivers of the EII frequency are identified, including magnetic field strength and the outgassing rate. Energetic electrons are correlated to the Rosetta-upstream solar wind potential difference, confirming that the ionizing electrons are solar wind electrons accelerated by an ambipolar field. The collisional test particle model incorporates a spherically symmetric, pure water coma and all the relevant electron-neutral collision processes. Electric and magnetic fields are stationary model inputs, and are computed using a fully-kinetic, collisionless Particle-in-Cell simulation. Collisional electrons are modelled at outgassing rates of $Q=10^{26}$ s$^{-1}$ and $Q=1.5\times10^{27}$ s$^{-1}$. Secondary electrons are the dominant population within a weakly outgassing comet. These are produced by collisions of solar wind electrons with the neutral coma. The implications of large ion flow speed estimates at Rosetta, away from perihelion, are discussed in relation to multi-instrument studies and the new results of the EII frequency obtained in the present study.

Authors:Alysa Obertas, Daniel Tamayo, Norm Murray

Abstract: Current planet formation theories rely on initially compact orbital configurations undergoing a (possibly extended) phase of giant impacts following the dispersal of the dissipative protoplanetary disk. The orbital architectures of observed mature exoplanet systems have likely been strongly sculpted by chaotic dynamics, instabilities, and giant impacts. One possible signature of systems continually reshaped by instabilities and mergers is their dynamical packing. Early Kepler data showed that many multi-planet systems are maximally packed - placing an additional planet between an observed pair would make the system unstable. However, this result relied on placing the inserted planet in the most optimistic configuration for stability (e.g., circular orbits). While this would be appropriate in an ordered and dissipative picture of planet formation (i.e. planets dampen into their most stable configurations), we argue that this best-case scenario for stability is rarely realized due to the strongly chaotic nature of planet formation. Consequently, the degree of dynamical packing in multi-planet systems under a realistic formation model is likely significantly higher than previously realized. We examine the full Kepler multi planet sample through this new lens, showing that ~60-95% of Kepler multi-planet systems are strongly packed and that dynamical packing increases with multiplicity. This may be a signature of dynamical sculpting or of undetected planets, showing that dynamical packing is an important metric that can be incorporated into planet formation modelling or when searching for unseen planets.

Authors:Juan C. Zapata Trujillo, Maria M. Pettyjohn, Laura K. McKemmish

Abstract: The identification of molecules in exoplanetary atmospheres is only possible thanks to the availability of high-resolution molecular spectroscopic data. However, due to its intensive and time-consuming generation process, at present, only on order 100 molecules have high-resolution spectroscopic data available, limiting new molecular detections. Using routine quantum chemistry calculations (i.e., scaled harmonic frequency calculations using the B97-1/def2-TZVPD model chemistry with median errors of 10cm-1), here we present a complementary high-throughput approach to rapidly generate approximate vibrational spectral data for 2743 molecules made from the biologically most important elements C, H, N, O, P and S. Though these data are not accurate enough to enable definitive molecular detections and does not seek to replace the need for high-resolution data, it has powerful applications in identifying potential molecular candidates responsible for unknown spectral features. We explore this application for the 4.1 micron (2439cm-1) feature in the atmospheric spectrum of WASP-39b, listing potential alternative molecular species responsible for this spectral line, together with SO2. Further applications of this big data compilation also include identifying molecules with strong absorption features that are likely detectable at quite low abundances, and training set for machine learning predictions of vibrational frequencies. Characterising exoplanetary atmospheres through molecular spectroscopy is essential to understand the planet's physico-chemical processes and likelihood of hosting life. Our rapidly generated quantum chemistry big data set will play a crucial role in supporting this understanding by giving directions into possible initial identifications of the more unusual molecules to emerge.

Authors:Marcel M. Popescu, O. Văduvescu, Julia de León, C. de la Fuente Marcos, R. de la Fuente Marcos, M. O. Stănescu, M. R. Alarcon, M. Serra Ricart, J. Licandro, D. Berteşteanu, M. Predatu, L. Curelaru, F. Barwell, K. Jhass, C. Boldea, A. Aznar Macías, L. Hudin, B. A. Dumitru

Abstract: Near-Earth asteroids (NEAs) that may evolve into impactors deserve detailed threat assessment studies. Early physical characterization of a would-be impactor may help in optimizing impact mitigation plans. We first detected NEA 2023~DZ$_{2}$ on 27--February--2023. After that, it was found to have a Minimum Orbit Intersection Distance (MOID) with Earth of 0.00005~au as well as an unusually high initial probability of becoming a near-term (in 2026) impactor. We aim to perform a rapid but consistent dynamical and physical characterization of 2023~DZ$_{2}$ as an example of a key response to mitigate the consequences of a potential impact. We use a multi-pronged approach, drawing from various methods (observational/computational) and techniques (spectroscopy/photometry from multiple instruments), and bringing the data together to perform a rapid and robust threat assessment.} The visible reflectance spectrum of 2023~DZ$_{2}$ is consistent with that of an X-type asteroid. Light curves of this object obtained on two different nights give a rotation period $P$=6.2743$\pm$0.0005 min with an amplitude $A$=0.57$\pm$0.14~mag. We confirm that although its MOID is among the smallest known, 2023~DZ$_{2}$ will not impact Earth in the foreseeable future as a result of secular near-resonant behaviour. Our investigation shows that coordinated observation and interpretation of disparate data provides a robust approach from discovery to threat assessment when a virtual impactor is identified. We prove that critical information can be obtained within a few days after the announcement of the potential impactor.

Authors:Sanne Bloot, Yamila Miguel, Michaël Bazot, Saburo Howard

Abstract: The mass and distribution of metals in the interiors of exoplanets are essential for constraining their formation and evolution processes. Nevertheless, with only masses and radii measured, the determination of exoplanet interior structures is degenerate, and so far simplified assumptions have mostly been used to derive planetary metallicities. In this work, we present a method based on a state-of-the-art interior code, recently used for Jupiter, and a Bayesian framework, to explore the possibility of retrieving the interior structure of exoplanets. We use masses, radii, equilibrium temperatures, and measured atmospheric metallicities to retrieve planetary bulk metallicities and core masses. Following results on the giant planets in the solar system and recent development in planet formation, we implement two interior structure models: one with a homogeneous envelope and one with an inhomogeneous one. Our method is first evaluated using a test planet and then applied to a sample of 37 giant exoplanets with observed atmospheric metallicities from the pre-JWST era. Although neither internal structure model is preferred with the current data, it is possible to obtain information on the interior properties of the planets, such as the core mass, through atmospheric measurements in both cases. We present updated metal mass fractions, in agreement with recent results on giant planets in the solar system.

Authors:E. Frattin, J. Martikainen, O. Muñoz, J. C. Gómez-Martín, T. Jardiel, A. Cellino, G. Libourel, K. Muinonen, M. Peiteado, P. Tanga

Abstract: We explore experimentally possible explanations of the polarization curves of the sunlight reflected by the Barbarian asteroids. Their peculiar polarization curves are characterized by a large inversion angle, around 30 degrees, which could be related to the presence of FeO-bearing spinel embedded in Calcium-Aluminum Inclusions. In order to test this hypothesis, we have measured the phase function and degree of linear polarization of six samples of Mg-rich olivine and spinel. For each material, we have analyzed the light scattering properties of a millimeter-sized grain and of two powdered samples with size distributions in the micrometer size range. The three spinel samples show a well-defined negative polarization branch with an inversion phase angle located around 24-30 degrees. In contrast, in the case of the olivine samples, the inversion angle is highly dependent on particle size and tends to decrease for larger sizes. We identify the macroscopic geometries as a possible explanation for the evident differences in the polarization curves between olivine and spinel millimeter samples. Although the polarization behaviour in near backscattering of the Barbara asteroid is similar to that of our spinel mm-sized sample in random orientation, this similarity could result in part from crystal retro-reflection rather than composition. This is part of an ongoing experimental project devoted to test separately several components of CV3-like meteorites, representative of the Barbarians composition, to disentangle their contributions to the polarization behavior of these objects.

Authors:Hikaru Hyuga, Yuichiro Cho, Seiji Sugita

Abstract: Many in situ potassium-argon (K-Ar) dating instruments under development use laser ablation to perform local analyses of several hundred um on rocks. Laser-induced breakdown spectroscopy (LIBS) and noble gas mass spectrometry (MS) are combined to achieve multiple spot analyses of the same rock to obtain K-Ar isochrons. The range and error of the data points on an isochron determine the accuracy and precision of dating. The range of the data on the isochron is governed by the relationship between the laser spot size and mineral size in the target rocks. A smaller laser spot size increases the range of the measured K concentration but decreases the amount of Ar extracted, which deteriorates the measurement accuracy. Because of this trade-off, the optimal laser spot size, which would give the best dating accuracy, would be somewhere in the middle. The mineral composition and spatial distribution in Martian rocks determine this optimum spot size. However, no extensive studies have been conducted to consider optimum laser spot size taking the mineral compositions of Martian rocks into account. Thus, it has been unknown how accurate the LIBS-MS method can be for in situ dating on Mars. In this study, we quantify the precision of dating Martian rocks by the LIBS-MS method and determine the instrumental conditions necessary for achieving the required precision. The dating precision was quantitatively evaluated by simulating isochrons that reflect the mineral composition of Martian rocks, which were obtained with electron probe microanalysis of three Martian meteorites. Our results indicate that a dating precision of 200 Myr could be achieved by reducing the laser spot size to 250 um and improving the measurement accuracy of K and Ar concentrations to 10%. We determined the instrumental conditions necessary to achieve the required dating precision for the LIBS-MS instrument currently developing.

Authors:Yuhito Shibaike, Yann Alibert

Abstract: Planetesimal formation is still mysterious. One of the ways to form planetesimals is to invoke a gas pressure bump in a protoplanetary disc. In our previous paper, we propose a new scenario in which the piled-up dust at a gas pressure bump created by a migrating planet form planetesimals by streaming instability in a wide region of the disc as the planet migrates inward. In this work, we consider the global time evolution of dust and investigate the detailed conditions and results of the planetesimal formation in our scenario. We use a 1D grid single-sized dust evolution model, which can follow the growth of the particles by their mutual collision and their radial drift and diffusion. We calculate the time-evolution of the radial distribution of the peak mass and surface density of the dust in a gas disc perturbed by an embedded migrating planet and investigate if the dust satisfies the condition for planetesimal formation. We find that planetesimals form in a belt-like region between the snowline and the position where the planet reaches its pebble-isolation mass when the strength of turbulence is $10^{-4}\leq\alpha\leq10^{-3}$, which is broadly consistent with observed value. The mechanism of the formation, streaming instability or mutual collision, depends on the timescale of the streaming instability. The total mass of planetesimals also depends on $\alpha$ and is about $30-100~M_{\rm E}$ if the planetary core has already existed at the beginning and grows by gas accretion, but it decreases as the timing of the formation of the planetary core is later. We also provide simple approximate expressions of the surface density and total mass of the planetesimals and find that the total mass strongly depends on the dust mass. We show that planetesimals form in a belt-like region by the combination of the dust pile-up at the gas pressure bump formed by a planet and its inward migration.

Authors:P. Nazari, B. Tabone, M. L. R. van 't Hoff, J. K. Jørgensen, E. F. van Dishoeck

Abstract: Earth is deficient in carbon and nitrogen by up to ${\sim}4$ orders of magnitude compared with the Sun. Destruction of (carbon- and nitrogen-rich) refractory organics in the high-temperature planet forming regions could explain this deficiency. Assuming a refractory cometary composition for these grains, their destruction enhances nitrogen-containing oxygen-poor molecules in the hot gas ($\gtrsim 300$K) after the initial formation and sublimation of these molecules from oxygen-rich ices in the warm gas (${\sim}150$K). Using observations of $37$ high-mass protostars with ALMA, we find that oxygen-containing molecules (CH$_3$OH and HNCO) systematically show no enhancement in their hot component. In contrast, nitrogen-containing, oxygen-poor molecules (CH$_3$CN and C$_2$H$_3$CN) systematically show an enhancement of a factor ${\sim} 5$ in their hot component, pointing to additional production of these molecules in the hot gas. Assuming only thermal excitation conditions, we interpret these results as a signature of destruction of refractory organics, consistent with the cometary composition. This destruction implies a higher C/O and N/O in the hot gas than the warm gas, while, the exact values of these ratios depend on the fraction of grains that are effectively destroyed. This fraction can be found by future chemical models that constrain C/O and N/O from the abundances of minor carbon, nitrogen and oxygen carriers presented here.

Authors:Jonathan Gomez Barrientos, Lisa Kaltenegger, Ryan J. MacDonald

Abstract: The recently discovered transiting super-Earth LP 890-9 c is potentially one of the best rocky exoplanets for atmospheric characterization. Orbiting an ultracool M-dwarf at the inner edge of the habitable zone, LP 890-9 c offers a new opportunity to study the climate of rocky planets at the inner edge of the habitable zone. We investigate the molecular detectability with simulated JWST transmission spectra for five potential atmospheres of LP 890-9 c. We find that a small three-transit JWST program can infer evidence of H2O (at 3$\sigma$ confidence) for a full runaway greenhouse scenario. Alternatively, CO2-dominated atmospheres resembling Venus without high-altitude terminator clouds can be identified with eight transits. However, these predictions could be complicated by the impact of clouds and/or unocculted starspots. Nevertheless, JWST observations of LP 890-9 c could provide critical insights and potentially distinguish between models of rocky planets at the inner edge of the habitable zone.

Authors:Larry R. Nittler, Asmaa Boujibar, Ellen Crapster-Pregont, Elizabeth A. Frank, Timothy J. McCoy, Francis M. McCubbin, Richard D. Starr, Audrey Vorburger, Shoshana Z. Weider

Abstract: Mercury, the innermost planet, formed under highly reduced conditions, based mainly on surface Fe, S, and Si abundances determined from MESSENGER mission data. The minor element Cr may serve as an independent oxybarometer, but only very limited Cr data have been previously reported for Mercury. We report Cr/Si abundances across Mercury's surface based on MESSENGER X-Ray Spectrometer data throughout the spacecraft's orbital mission. The heterogeneous Cr/Si ratio ranges from 0.0015 in the Caloris Basin to 0.0054 within the high-magnesium region, with an average southern hemisphere value of 0.0008 (corresponding to about 200 ppm Cr). Absolute Cr/Si values have systematic uncertainty of at least 30%, but relative variations are more robust. By combining experimental Cr partitioning data along with planetary differentiation modeling, we find that if Mercury formed with bulk chondritic Cr/Al, Cr must be present in the planet's core and differentiation must have occurred at log fO2 in the range of IW-6.5 to IW-2.5 in the absence of sulfides in its interior, and a range of IW-5.5 to IW-2 with an FeS layer at the core-mantle boundary. Models with large fractions of Mg-Ca-rich sulfides in Mercury's interior are more compatible with moderately reducing conditions (IW-5.5 to IW-4) owing to the instability of Mg-Ca-rich sulfides at elevated fO2. These results indicate that if Mercury differentiated at a log fO2 lower than IW-5.5, the presence of sulfides whether in the form of a FeS layer at the top of the core or Mg-Ca-rich sulfides within the mantle would be unlikely.

Authors:Dorian S. Abbot, Robert J. Webber, David M. Hernandez, Sam Hadden, Jonathan Weare

Abstract: Mercury's orbit can destabilize, resulting in a collision with either Venus or the Sun. Chaotic evolution can cause $g_1$ to decrease to the approximately constant value of $g_5$ and create a resonance. Previous work has approximated the variation in $g_1$ as stochastic diffusion, which leads to a model that can reproduce the Mercury instability statistics of secular and $N$-body models on timescales longer than 10~Gyr. Here we show that the diffusive model underpredicts the Mercury instability probability by a factor of 3-10,000 on timescales less than 5~Gyr, the remaining lifespan of the Solar System. This is because $g_1$ exhibits larger variations on short timescales than the diffusive model would suggest. To better model the variations on short timescales, we build a new subdiffusive model for $g_1$ including a quadratic spring potential above a certain value of $g_1$, which we refer to as a soft upper boundary. Subdiffusion is similar to diffusion, but exhibits larger displacements on short timescales and smaller displacements on long timescales. We choose model parameters based on the short-time behavior of the $g_1$ trajectories in the $N$-body simulations, leading to a tuned model that can reproduce Mercury instability statistics from 1-40~Gyr. This work motivates several questions in planetary dynamics: Why does subdiffusion better approximate the variation in $g_1$ than standard diffusion? Why is a soft upper boundary condition on $g_1$ an appropriate approximation? Why is there an upper bound on $g_1$, but not a lower bound that would prevent it from reaching $g_5$?

Authors:Audrey Vorburger, Peter Wurz, Hunter Waite

Abstract: So far no designated mission to either of the two ice giants, Uranus and Neptune, exists. Almost all of our gathered information on these planets comes from remote sensing. In recent years, NASA and ESA have started planning for future mission to Uranus and Neptune, with both agencies focusing their attention on orbiters and atmospheric probes. Whereas information provided by remote sensing is undoubtedly highly valuable, remote sensing of planetary atmospheres also presents some shortcomings, most of which can be overcome by mass spectrometers. In most studies presented to date a mass spectrometer experiment is thus a favored science instrument for in situ composition measurements on an atmospheric probe. Mass spectrometric measurements can provide unique scientific data, i.e., sensitive and quantitative measurements of the chemical composition of the atmosphere, including isotopic, elemental, and molecular abundances. In this review paper we present the technical aspects of mass spectrometry relevant to atmospheric probes. This includes the individual components that make up mass spectrometers and possible implementation choices for each of these components. We then give an overview of mass spectrometers that were sent to space with the intent of probing planetary atmospheres, and discuss three instruments, the heritage of which is especially relevant to Uranus and Neptune probes, in detail. The main part of this paper presents the current state-of-art in mass spectrometry intended for atmospheric probe. Finally, we present a possible descent probe implementation in detail, including measurement phases and associated expected accuracies for selected species.

Authors:Alberto Fossà, Matteo Losacco, Roberto Armellin

Abstract: An algorithm for robust initial orbit determination (IOD) under perturbed orbital dynamics is presented. By leveraging map inversion techniques defined in the algebra of Taylor polynomials, this tool is capable of not only returning an highly accurate solution to the IOD problem, but also estimating a range of validity for the aforementioned solution in which the true orbit state should lie. Automatic domain splitting is then used on top of the IOD routines to ensure the local truncation error introduced by a polynomial representation of the state estimate remains below a predefined threshold to meet the specified requirements in accuracy. The algorithm is adapted to three types of ground based sensors, namely range radars, Doppler-only radars and optical telescopes by taking into account their different constraints in terms of available measurements and sensor noise. Its improved performance with respect to a Keplerian based IOD solution is finally demonstrated with large scale numerical simulations over a subset of tracked objects in low Earth orbit.

Authors:James Terrill, Sebastian Marino, Richard A. Booth, Yinuo Han, Jeff Jennings, Mark C. Wyatt

Abstract: Constraining the vertical and radial structure of debris discs is crucial to understanding their formation, evolution and dynamics. To measure both the radial and vertical structure, a disc must be sufficiently inclined. However, if a disc is too close to edge-on, deprojecting its emission becomes non-trivial. In this paper we show how Frankenstein, a non-parametric tool to extract the radial brightness profile of circumstellar discs, can be used to deproject their emission at any inclination as long as they are optically thin and axisymmetric. Furthermore, we extend Frankenstein to account for the vertical thickness of an optically thin disc ($H(r)$) and show how it can be constrained by sampling its posterior probability distribution and assuming a functional form (e.g. constant $h=H/r$), while fitting the radial profile non-parametrically. We use this new method to determine the radial and vertical structure of 16 highly inclined debris discs observed by ALMA. We find a wide range of vertical aspect ratios, $h$, ranging from $0.020\pm0.002$ (AU Mic) to $0.20\pm0.03$ (HD 110058), which are consistent with parametric models. We find a tentative correlation between $h$ and the disc fractional width, as expected if wide discs were more stirred. Assuming discs are self-stirred, the thinnest discs would require the presence of at least 500 km-sized planetesimals. The thickest discs would likely require the presence of planets. We also recover previously inferred and new radial structures, including a potential gap in the radial distribution of HD 61005. Finally, our new extension of Frankenstein also allows constraining how $h$ varies as a function of radius, which we test on 49 Ceti, finding that $h$ is consistent with being constant.

Authors:Faith Hawthorn, Daniel Bayliss, David J. Armstrong, Jorge Fernández Fernández, Ares Osborn, Sérgio G. Sousa, Vardan Adibekyan, Jeanne Davoult, Karen A. Collins, Yann Alibert, Susana C. C. Barros, François Bouchy, Matteo Brogi, David R. Ciardi, Tansu Daylan, Elisa Delgado Mena, Olivier D. S. Demangeon, Rodrigo F. Díaz, Tianjun Gan, Keith Horne, Sergio Hoyer, Alan M. Levine, Jorge Lillo-Box, Louise D. Nielsen, Hugh P. Osborn, George R. Ricker, José Rodrigues, Nuno C. Santos, Richard P. Schwarz, Sara Seager, Juan Serrano Bell, Avi Shporer, Chris Stockdale, Paul A. Strøm, Peter Tenenbaum, Stéphane Udry, Peter J. Wheatley, Joshua N. Winn, Carl Ziegler

Abstract: We present the discovery of an exoplanet transiting TOI-908 (TIC-350153977) using data from TESS sectors 1, 12, 13, 27, 28 and 39. TOI-908 is a T = 10.7 mag G-dwarf ($T_{eff}$ = 5626 $\pm$ 61 K) solar-like star with a mass of 0.950 $\pm$ 0.010 $M_{\odot}$ and a radius of 1.028 $\pm$ 0.030 $R_{\odot}$. The planet, TOI-908 b, is a 3.18 $\pm$ 0.16 $R_{\oplus}$ planet in a 3.18 day orbit. Radial velocity measurements from HARPS reveal TOI-908 b has a mass of approximately 16.1 $\pm$ 4.1 $M_{\oplus}$ , resulting in a bulk planetary density of 2.7+0.2-0.4 g cm-3. TOI-908 b lies in a sparsely-populated region of parameter space known as the Neptune desert. The planet likely began its life as a sub-Saturn planet before it experienced significant photoevaporation due to X-rays and extreme ultraviolet radiation from its host star, and is likely to continue evaporating, losing a significant fraction of its residual envelope mass.

Authors:Edoardo Legnaro, Christos Efthymiopoulos, Maria Harsoula

Abstract: We discuss the applicability of the Melnikov and Landau-Teller theories in obtaining semi-analytical estimates of the speed of chaotic diffusion in systems driven by the separatrix-like stochastic layers of a resonance belonging to the `second fundamental model' (SFM)\cite{henrard1983second}. Stemming from the analytic solution for the SFM in terms of Weierstrass elliptic functions, we introduce stochastic Melnikov and Landau-Teller models allowing to locally approximate chaotic diffusion as a sequence of uncorrelated `jumps' observed in the time series yielding the slow evolution of an ensemble of trajectories in the space of the adiabatic actions of the system. Such jumps occur in steps of one per homoclinic loop. We show how a semi-analytical determination of the probability distribution of the size of the jumps can be arrived at by the Melnikov and Landau-Teller approximate theories. Computing also the mean time required per homoclinic loop, we arrive at estimates of the chaotic diffusion coefficient in such systems. As a concrete example, we refer to the long-term diffusion of a small object (e.g. Earth navigation satellite or space debris) within the chaotic layers of the so-called $2g+h$ lunisolar resonance, which is of the SFM type. After a suitable normal form reduction of the Hamiltonian, we compute estimates of the speed of diffusion of these objects, which compare well with the results of numerical experiments.

Authors:Philipp Baumeister, Nicola Tosi

Abstract: Characterizing the interior structure of exoplanets is essential for understanding their diversity, formation, and evolution. As the interior of exoplanets is inaccessible to observations, an inverse problem must be solved, where numerical structure models need to conform to observable parameters such as mass and radius. This is a highly degenerate problem whose solution often relies on computationally-expensive and time-consuming inference methods such as Markov Chain Monte Carlo. We present ExoMDN, a machine-learning model for the interior characterization of exoplanets based on Mixture Density Networks (MDN). The model is trained on a large dataset of more than 5.6 million synthetic planets below 25 Earth masses consisting of an iron core, a silicate mantle, a water and high-pressure ice layer, and a H/He atmosphere. We employ log-ratio transformations to convert the interior structure data into a form that the MDN can easily handle. Given mass, radius, and equilibrium temperature, we show that ExoMDN can deliver a full posterior distribution of mass fractions and thicknesses of each planetary layer in under a second on a standard Intel i5 CPU. Observational uncertainties can be easily accounted for through repeated predictions from within the uncertainties. We use ExoMDN to characterize the interior of 22 confirmed exoplanets with mass and radius uncertainties below 10% and 5% respectively, including the well studied GJ 1214 b, GJ 486 b, and the TRAPPIST-1 planets. We discuss the inclusion of the fluid Love number $k_2$ as an additional (potential) observable, showing how it can significantly reduce the degeneracy of interior structures. Utilizing the fast predictions of ExoMDN, we show that measuring $k_2$ with an accuracy of 10% can constrain the thickness of core and mantle of an Earth analog to $\approx13\%$ of the true values.

Authors:Misako Tatsuuma, Akimasa Kataoka, Satoshi Okuzumi, Hidekazu Tanaka

Abstract: Compressive strength is a key to understanding the internal structure of dust aggregates in protoplanetary disks and their resultant bodies, such as comets and asteroids in the Solar System. Previous work has modeled the compressive strength of highly-porous dust aggregates with volume filling factors lower than 0.1. However, a comprehensive understanding of the compressive strength from low ($<0.1$) to high ($>0.1$) volume filling factors is lacking. In this paper, we investigate the compressive strength of dust aggregates by using aggregate compression simulations resolving constituent grains based on JKR theory to formulate the compressive strength comprehensively. We perform a series of numerical simulations with moving periodic boundaries mimicking the compression behavior. As a result, we find that the compressive strength becomes sharply harder when the volume filling factor exceeds 0.1. We succeed in formulating the compressive strength comprehensively by taking into account the rolling motion of aggregates for low volume filling factors and the closest packing of aggregates for high volume filling factors. We also find that the dominant compression mechanisms for high volume filling factors are sliding and twisting motions, while rolling motion dominates for low volume filling factors. We confirm that our results are in good agreement with previous numerical studies. We suggest that our analytical formula is consistent with the previous experimental results if we assume the surface energy of silicate is $\simeq210\pm90\mathrm{\ mJ\ m^{-2}}$. Now, we can apply our results to properties of small compact bodies, such as comets, asteroids, and pebbles.

Authors:Chen Xie, Bin B. Ren, Ruobing Dong, Élodie Choquet, Arthur Vigan, Jean-François Gonzalez, Kevin Wagner, Taotao Fang, Maria Giulia Ubeira-Gabellini

Abstract: Radio and near-infrared observations have observed dozens of protoplanetary disks that host spiral arm features. Numerical simulations have shown that companions may excite spiral density waves in protoplanetary disks via companion-disk interaction. However, the lack of direct observational evidence for spiral-driving companions poses challenges to current theories of companion-disk interaction. Here we report multi-epoch observations of the binary system HD 100453 with the Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) facility at the Very Large Telescope. By recovering the spiral features via robustly removing starlight contamination, we measure spiral motion across 4 yr to perform dynamical motion analyses. The spiral pattern motion is consistent with the orbital motion of the eccentric companion. With this first observational evidence of a companion driving a spiral arm among protoplanetary disks, we directly and dynamically confirm the long-standing theory on the origin of spiral features in protoplanetary disks. With the pattern motion of companion-driven spirals being independent of companion mass, here we establish a feasible way of searching for hidden spiral-arm-driving planets that are beyond the detection of existing ground-based high-contrast imagers.

Authors:Marco Fenucci, Bojan Novaković, Dušan Marčeta

Abstract: Asteroids smaller than about 100 meters are observed to rotate very fast, with periods often much shorter than the critical limit of 2.2 h. Some of these super-fast rotators can also achieve a very large semi-major axis drift induced by the Yarkovsky effect, that in turn, is determined by internal and surface physical properties. We consider the small super-fast rotating near-Earth asteroid 2016 GE1. This object rotates in just 34 seconds, and a large Yarkovsky effect has been determined from astrometry. Here we aim to constrain the thermal inertia of the surface of this extreme object. We used a recently developed statistical method to determine the thermal properties of near-Earth asteroids. The method is based on the comparison between the observed and the modelled Yarkovsky effect, and the thermal conductivity (inertia) is determined by a Monte Carlo approach. Parameters of the Yarkovsky effect model are either fixed if their uncertainty is negligible, modelled with a Gaussian distribution of the errors if they are measured, or deduced from general properties of the population of near-Earth asteroids when they are unknown. Using a well-established orbit determination procedure, we determined the Yarkovsky effect on 2016 GE1, and verified a significant semi-major axis drift rate. Using a statistical method, we showed that this semi-major axis drift rate could be explained only by low thermal inertia values below 100 J m$^{-2}$ K$^{-1}$ s$^{-1/2}$: namely, 90\% of the probability density function of the model outcomes is contained at values smaller than 100 J m$^{-2}$ K$^{-1}$ s$^{-1/2}$. We propose two possible interpretations for the extremely low values: a high porosity or a cracked surface, or a thin layer of fine regolith on the surface. Though this seems unexpected in either case, it opens up the possibility of a subclass of low thermal inertia, super-fast rotating asteroids.

Authors:Salvatore Ferrone, Marco Delbo, Chrysa Avdellidou, Rogerio Deienno, Robert Melikyan, Kevin Walsh, Alessandro Morbidelli

Abstract: After performing a reassessment of the known dynamical asteroid families in the inner main belt, we report a newly discovered ancient asteroid family with an estimated age of $4.3\pm1.7$ billion years. Additionally, we report the most comprehensive list of planetesimals, which are asteroids that survived since the planet forming days of the solar system.

Authors:Viktor T. Toth, Slava G. Turyshev

Abstract: We utilize the well-established properties of the solar gravitational lens (SGL) to consider realistic observational scenarios. Actual exoplanets, which may be the target of an SGL observational campaign, are not stationary. Their appearance changes as a result of their diurnal rotation and varying illumination due to their orbital motion around their host star. The nature of the SGL is such that imaging with one telescope is accomplished with a cadence of one pixel at a time, with substantial per-pixel integration times. Therefore, capturing a single snapshot of the target planet with a realistically-sized telescope is not possible. Instead, the planetary surface must be reconstructed by inverting the combined effect of the SGL's point-spread function and temporal changes induced by the planetary dynamics. Using the Earth as a stand-in, we demonstrate practical feasibility of this approach, by simulating a dynamical system and then recovering topographic images of acceptable quality. The dynamics-induced temporal variability of the exoplanet represents an added challenge, but even in the presence of such dynamics, use of the SGL for exoplanet imaging remains feasible.

Authors:Bhavesh Jaiswal

Abstract: Direct imaging of exoplanets will allow us to directly observe the planet in reflected light. Such a scenario may eventually allow for the possibility to scan the planetary surface for the presence of artificial structures made by alien civilizations. Detectability of planetary scale structures, called megastructures, has been previously explored. In this work, we show that it is possible to detect structures of much smaller scale on exoplanetary surfaces by searching for the specular reflection of host starlight from the corresponding structures. As the planet rotates, these reflections can manifest as an optical transient riding atop the rotational light curve of the planet. Due to the directional nature of specular reflection, the reflected signal is very strong, and it is comparable to the planetary flux for surfaces covering only few ppm (parts per million) of the total planet surface area. By tracking the planet around its orbit, it should be possible to scan the planetary surface for any such structures covering a size larger than a few ppm of planetary surface. The proposed method will aid in the search for extra-terrestrial intelligence in the era of direct imaging of exoplanets.

Authors:Matija Ćuk, Maryame El Moutamid

Abstract: Saturn possesses a dynamically rich system containing numerous moons and impressive rings. Whether the rings of Saturn are much younger than the planet itself has been a long-open question; more recently a young age has been proposed for some moons. Recent detection of the fast orbital evolution of Rhea and Titan strongly suggest a highly frequency-dependent tidal response of Saturn, possibly through excitation of inertial waves within the planet's convective envelope. Here we show that the resonance locking to inertial waves cannot explain the dynamical structure of the Saturnian system or the current tidal heating of Enceladus. On the other hand, both the observation and our modelling results indicate that the system is not consistent with evolution under equilibrium tides. We propose that the system's architecture can best be explained by relatively high "background" tidal response coupled with discrete resonant modes. In this view, only Titan may be in a true long-term resonance lock with a tidal mode of Saturn. Rhea is most likely currently experiencing a transient period of fast tidal evolution as it passes through a mode, rather than being locked to it. Assuming that Enceladus went through a temporary period of fast tidal evolution, we can reproduce its present resonance with Dione and satisfy other dynamical constraints. Additionally, we conclude that the long-term tidal response of Saturn to Tethys must be weaker than expected from frequency-independent tides, as already found by observations.

Authors:Josh Calcino, Daniel J. Price, Christophe Pinte, Himanshi Garg, Brodie J. Norfolk, Valentin Christiaens, Hui Li, Richard Teague

Abstract: We present five morphological and kinematic criteria to aid in asserting the binary nature of a protoplanetary disc, based on 3D hydrodynamical simulations of circumbinary discs post-processed with Monte Carlo radiative transfer. We find that circumbinary discs may be identified by i) a central cavity, ii) spiral arms both in and outside of their central cavities, iii) non-localised perturbations in their iso-velocity curves, iv) asymmetry between the lines of maximum speed of the blue and red-shifted wings and v) asymmetry between the area of the blue and red-shifted wings. We provide quantitative metrics for the last two criteria that can be used, in conjunction with the morphological criteria, to signal whether a protoplanetary disc is likely to be a circumbinary disc.

Authors:John M. Brewer, Lily L. Zhao, Debra A. Fischer, Rachael M. Roettenbacher, Gregory W. Henry, Joe Llama, Andrew E. Szymkowiak, Samuel H. C. Cabot, Sam A. Weiss, Chris McCarthy

Abstract: Thousands of exoplanet detections have been made over the last twenty-five years using Doppler observations, transit photometry, direct imaging, and astrometry. Each of these methods is sensitive to different ranges of orbital separations and planetary radii (or masses). This makes it difficult to fully characterize exoplanet architectures and to place our solar system in context with the wealth of discoveries that have been made. Here, we use the EXtreme PREcision Spectrograph (EXPRES) to reveal planets in previously undetectable regions of the mass-period parameter space for the star $\rho$ Coronae Borealis. We add two new planets to the previously known system with one hot Jupiter in a 39-day orbit and a warm super-Neptune in a 102-day orbit. The new detections include a temperate Neptune planet ($M{\sin{i}} \sim 20$ M$_\oplus$) in a 281.4-day orbit and a hot super-Earth ($M{\sin{i}} = 3.7$ M$_\oplus$) in a 12.95-day orbit. This result shows that details of planetary system architectures have been hiding just below our previous detection limits; this signals an exciting era for the next generation of extreme precision spectrographs.

Authors:Dion Linssen, Antonija Oklopčić

Abstract: Escaping exoplanet atmospheres have been observed as deep transit signatures in a few specific spectral lines. Detections have been made in the hydrogen Ly-$\alpha$ line, the metastable helium line at 10830 {\AA} and some UV lines of metallic species. Observational challenges, unexpected non-detections and model degeneracies have generally made it difficult to draw definitive conclusions about the escape process for individual planets. Expanding on the suite of spectral tracers used may help to mitigate these challenges. We present a new framework for modeling the transmission spectrum of hydrodynamically escaping atmospheres. We predict FUV to NIR spectra for systems with different planet and stellar types and identify new lines that can potentially be used to study their upper atmospheres. Measuring the radius in the atmosphere at which the strongest lines form puts them into context within the upper atmospheric structure. Targeting a set of complementary spectral lines for the same planet will help us to better constrain the outflow properties.

Authors:Dorothea Bischoff, Christian Schuckart, Nicholas Attree, Bastian Gundlach, Jürgen Blum

Abstract: The mechanism of dust emission from a cometary nucleus is still an open question and thermophysical models have problems reproducing outgassing and dust productions rates simultaneously. In this study, we investigate the capabilities of a rather simple thermophysical model to match observations from Rosetta instruments at comet 67P/Churyumov-Gerasimenko and the influence of model variations. We assume a macro-porous surface structure composed of pebbles and investigate the influence of different model assumptions. Besides the scenario in which dust layers are ejected when the vapour pressure overcomes the tensile strength, we use artificial ejection mechanisms, depending on ice-depletion of layers. We find that dust activity following the pressure criterion is only possible for reduced tensile strength values or reduced gas diffusivity and is inconsistent with observed outgassing rates, because activity is driven by CO$_2$. Only when we assume that dust activity is triggered when the layer is completely depleted in H$_2$O, the ratio of CO$_2$ to H$_2$O outgassing rates is in the expected order of magnitude. However, the dust-to-H$_2$O ratio is never reproduced. Only with decreased gas diffusivity, the slope of the H$_2$O outgassing rate is matched, however absolute values are too low. To investigate maximum reachable pressures, we adapted our model equivalent to a gas-impermeable dust structure. Here, pressures exceeding the tensile strength by orders of magnitude are possible. Maximum activity distances of $3.1 \,\mathrm{au}$, $8.2 \,\mathrm{au}$, and $74 \,\mathrm{au}$ were estimated for H$_2$O-, CO$_2$-, and CO-driven activity of $1 \,\mathrm{cm}$-sized dust, respectively. In conclusion, the mechanism behind dust emission remains unclear.

Authors:Vincenzo Mariani, Agnès Fienga, Olivier Minazzoli, Mickaël Gastineau, Jacques Laskar

Abstract: In this work, we investigated Bayesian methodologies for constraining in the Solar System a Yukawa suppression of the Newtonian potential -- which we interpret as the effect of a non-null graviton mass -- by considering its impact on planetary orbits. Complementary to the previous results obtained with INPOP planetary ephemerides, we consider here a Markov Chain Monte Carlo approach associated with a Gaussian Process Regression for improving the resolution of the constraints driven by planetary ephemerides on the graviton mass in the Solar System. At the end of the procedure, a posterior for the mass of the graviton is presented, providing an upper bound at $1.01 \times 10^{-24} \; eV c^{-2}$ (resp. $\lambda_g \geq 122.48 \times 10^{13} \; km$) with a $99.7\%$ confidence level. The threshold value represents an improvement of 1 order of magnitude relative to the previous estimations. This updated determination of the upper bound is mainly due to the Bayesian methodology, although the use of new planetary ephemerides (INPOP21a used here versus INPOP19a used previously) already induces a gain of a factor 3 with respect to the previous limit. The INPOP21a ephemerides is characterized by the addition of new Juno and Mars orbiter data, but also by a better Solar System modeling, with notably a more realistic model of the Kuiper belt. Finally, by testing the sensitivity of our results to the choice of the $\textit{a priori}$ distribution of the graviton mass, it turns out that the selection of a prior more favorable to zero-mass graviton (that is, here, General Relativity) seems to be more supported by the observations than non-zero mass graviton, leading to a possible conclusion that planetary ephemerides are more likely to favor General Relativity.

Authors:Julius L. A. M. Hendrix, Amy J. Louca, Yamila Miguel

Abstract: In this era of exoplanet characterisation with JWST, the need for a fast implementation of classical forward models to understand the chemical and physical processes in exoplanet atmospheres is more important than ever. Notably, the time-dependent ordinary differential equations to be solved by chemical kinetics codes are very time-consuming to compute. In this study, we focus on the implementation of neural networks to replace mathematical frameworks in one-dimensional chemical kinetics codes. Using the gravity profile, temperature-pressure profiles, initial mixing ratios, and stellar flux of a sample of hot-Jupiters atmospheres as free parameters, the neural network is built to predict the mixing ratio outputs in steady state. The architecture of the network is composed of individual autoencoders for each input variable to reduce the input dimensionality, which is then used as the input training data for an LSTM-like neural network. Results show that the autoencoders for the mixing ratios, stellar spectra, and pressure profiles are exceedingly successful in encoding and decoding the data. Our results show that in 90% of the cases, the fully trained model is able to predict the evolved mixing ratios of the species in the hot-Jupiter atmosphere simulations. The fully trained model is ~1000 times faster than the simulations done with the forward, chemical kinetics model while making accurate predictions.

Authors:Nathan X. Roth, Stefanie N. Milam, Anthony J. Remijan, Martin A. Cordiner, Michael W. Busch, Cristina A. Thomas, Andrew S. Rivkin, Arielle Moullet, Ted L. Roush, Mark A. Siebert, Jian-Yang Li, Eugene G. Fahnestock, Josep M. Trigo-Rodriguez, Cyrielle Opitom, Masatoshi Hirabayashi

Abstract: We report observations of the Didymos-Dimorphos binary asteroid system using the Atacama Large Millimeter/Submillimeter Array (ALMA) and the Atacama Compact Array (ACA) in support of the Double Asteroid Redirection Test (DART) mission. Our observations on UT 2022 September 15 provided a pre-impact baseline and the first measure of Didymos-Dimorphos' spectral emissivity at $\lambda=0.87$ mm, which was consistent with the handful of siliceous and carbonaceous asteroids measured at millimeter wavelengths. Our post-impact observations were conducted using four consecutive executions each of ALMA and the ACA spanning from T+3.52 to T+8.60 hours post-impact, sampling thermal emission from the asteroids and the impact ejecta. We scaled our pre-impact baseline measurement and subtracted it from the post-impact observations to isolate the flux density of mm-sized grains in the ejecta. Ejecta dust masses were calculated for a range of materials that may be representative of Dimorphos' S-type asteroid material. Depending on the material assumed, the average ejecta mass over our observations is consistent with 0.9--5.2$\times10^7$ kg, representing 0.2--1.2% of Dimorphos' total mass and in agreement with ejecta mass estimates based on measurements at optical wavelengths. Our results provide the most sensitive measure of mm-sized material in the ejecta and demonstrate the power of ALMA for providing supporting observations to spaceflight missions.

Authors:Shi Jia, Wei Zhong, Cong Yu

Abstract: Super-Earth population, as one of the representatives of exoplanets, plays an important role in constraining the planet formation theories. According to the prediction from core-accretion models, super-Earths should be rare because their masses are in the range of the critical mass above which they would grow to be gas giants by runaway gas accretion. In this work, we investigate the effect of ohmic dissipation on the planetary thermal structure and cooling contraction as planets accrete gas from their surrounding disks. We find that the extra heating energy from Ohmic heating deposited into planetary envelopes can push the planetary radiative-convective boundaries inward and prevent the planets from cooling, and can even halt accretion. We explore parameter space to study the dependence of cooling timescale on the input parameters of the ohmic-dissipation model. Numerical results show that gas accretion can be halted before runaway gas accretion and the envelope mass is only several percent of planetary core mass for some parameter sets. Our results suggest that ohmic dissipation is a potential mechanism to delay the gas accretion and promote the formation of super-Earths. Future observations may help to constrain the importance of ohmic dissipation on the super-Earth formation.

Authors:Daniel Elsender, Matthew R. Bate, Ben S. Lakeland, Eric L. N. Jensen, Stephen H. Lubow

Abstract: We report the analysis of circumbinary discs formed in a radiation hydrodynamical simulation of star cluster formation. We consider both pure binary stars and pairs within triple and quadruple systems. The protostellar systems are all young (ages < $10^5$ yrs). We find that the systems that host a circumbinary disc have a median separation of $\approx 11$ au, and the median characteristic radius of the discs is $\approx 64$ au. We find that $89$ per cent of pure binaries with semi-major axes $a<1$ au have a circumbinary disc, and the occurrence rate of circumbinary discs is bimodal with log-separation in pure binaries with a second peak at $a \approx 50$ au. Systems with $a>100$ au almost never have a circumbinary disc. The median size of a circumbinary disc is between $\approx 5-6\ a$ depending on the order of the system, with higher order systems having larger discs relative to binary separation. We find the underlying distribution of mutual inclinations between circumbinary discs and binary orbit of both observed and simulated discs to not differ statistically.

Authors:Fabian Binkert

Abstract: Turbulence in protoplanetary disks, when present, plays a critical role in transporting dust particles embedded in the gaseous disk component. When using a field description of dust dynamics, a diffusion approach is traditionally used to model this turbulent dust transport. However, it has been shown that classical turbulent diffusion models are not fully self-consistent. Several shortcomings exist, including the ambiguous nature of the diffused quantity and the nonconservation of angular momentum. Orbital effects are also neglected without an explicit prescription. In response to these inconsistencies, we present a novel Eulerian turbulent dust transport model for isotropic and homogeneous turbulence on the basis of a mean-field theory. Our model is based on density-weighted averaging applied to the pressureless fluid equations and uses appropriate turbulence closures. Our model yields novel dynamic equations for the turbulent dust mass flux and recovers existing turbulent transport models in special limiting cases, thus providing a more general and self-consistent description of turbulent particle transport. Importantly, our model ensures the conservation of global angular and linear momentum unconditionally and implicitly accounts for the effects of orbital dynamics in protoplanetary disks. Furthermore, our model correctly describes the vertical settling-diffusion equilibrium solutions for both small and large particles. Hence, this work presents a generalized Eulerian turbulent dust transport model, establishing a comprehensive framework for more detailed studies of turbulent dust transport in protoplanetary disks.

Authors:Jian Li, S. M. Lawler, Hanlun Lei

Abstract: In our previous study of Neptune's 4:7 mean motion resonance (MMR), we discovered that its resonant angle can only librate within a specific eccentricity ($e$) versus inclination ($i$) region, determined by a theoretical limiting curve curve (Li et al. 2020). This ``permissible region'' is independent of time and encompasses the entire possible stable region. We now generalize this theory to investigate all high-order MMRs embedded in the main classical Kuiper belt (MCKB). We first consider the 2nd-order 3:5 MMR in the framework of planet migration and resonance capture, and have further validated our limiting curve theory for both captured and observed 3:5 resonators. It suggests that only the $(e, i)$ pairs inside the individual permissible regions should be chosen as initial conditions for studying the in-situ evolution of high-order resonators. With such a new setting, we proceed to explore the long-term stability (for 4 Gyr) of different resonant populations, and our simulations predict that: (1) the 3:5 and 4:7 resonators are comparable in number, and they could have inclinations up to $40^{\circ}$; (2) the populations of objects in the higher order 5:9, 6:11, 7:12 and 7:13 resonances is about 1/10 of the 3:5 (or 4:7) resonator population, and nearly all of them are found on the less inclined orbits with $i<10^{\circ}$; (3) for these high-order resonances, almost all resonators reside in their individual permissible regions. In summary, our results make predictions for the number and orbital distributions of potential resonant objects that will be discovered in the future throughout the MCKB.

Authors:Michelle Kunimoto, Andrew Vanderburg, Chelsea X. Huang, M. Ryleigh Davis, Laura Affer, Andrew Collier Cameron, David Charbonneau, Rosario Cosentino, Mario Damasso, Xavier Dumusque, A. F. Martnez Fiorenzano, Adriano Ghedina, R. D. Haywood, Florian Lienhard, Mercedes López-Morales, Michel Mayor, Francesco Pepe, Matteo Pinamonti, Ennio Poretti, Jesús Maldonado, Ken Rice, Alessandro Sozzetti, Thomas G. Wilson, Stéphane Udry, Jay Baptista, Khalid Barkaoui, Juliette Becker, Paul Benni, Allyson Bieryla, Pau Bosch-Cabot, David R. Ciardi, Karen A. Collins, Kevin I. Collins, Elise Evans, Trent J. Dupuy, Maria V. Goliguzova, Pere Guerra, Adam Kraus, Jack J. Lissauer, Daniel Huber, Felipe Murgas, Enric Palle, Samuel N. Quinn, Boris S. Safonov, Richard P. Schwarz, Avi Shporer, Keivan G. Stassun, Jon M. Jenkins, David W. Latham, George R. Ricker, Sara Seager, Roland Vanderspek, Joshua Winn, Zahra Essack, Hannah M. Lewis, Mark E. Rose

Abstract: We report the confirmation of three exoplanets transiting TOI-4010 (TIC-352682207), a metal-rich K dwarf observed by TESS in Sectors 24, 25, 52, and 58. We confirm these planets with HARPS-N radial velocity observations and measure their masses with 8 - 12% precision. TOI-4010 b is a sub-Neptune ($P = 1.3$ days, $R_{p} = 3.02_{-0.08}^{+0.08}~R_{\oplus}$, $M_{p} = 11.00_{-1.27}^{+1.29}~M_{\oplus}$) in the hot Neptune desert, and is one of the few such planets with known companions. Meanwhile, TOI-4010 c ($P = 5.4$ days, $R_{p} = 5.93_{-0.12}^{+0.11}~R_{\oplus}$, $M_{p} = 20.31_{-2.11}^{+2.13}~M_{\oplus}$) and TOI-4010 d ($P = 14.7$ days, $R_{p} = 6.18_{-0.14}^{+0.15}~R_{\oplus}$, $M_{p} = 38.15_{-3.22}^{+3.27}~M_{\oplus}$) are similarly-sized sub-Saturns on short-period orbits. Radial velocity observations also reveal a super-Jupiter-mass companion called TOI-4010 e in a long-period, eccentric orbit ($P \sim 762$ days and $e \sim 0.26$ based on available observations). TOI-4010 is one of the few systems with multiple short-period sub-Saturns to be discovered so far.

Authors:Joshua Krissansen-Totton

Abstract: JWST secondary eclipse observations of Trappist-1b seemingly disfavor atmospheres >~1 bar since heat redistribution is expected to yield dayside emission temperature below the ~500 K observed. Given the similar densities of Trappist-1 planets, and the theoretical potential for atmospheric erosion around late M-dwarfs, this observation might be assumed to imply substantial atmospheres are also unlikely for the outer planets. However, the processes governing atmosphere erosion and replenishment are fundamentally different for inner and outer planets. Here, an atmosphere-interior evolution model is used to show that an airless Trappist-1b (and c) only weakly constrains stellar evolution, and that the odds of outer planets e and f retaining substantial atmospheres remain largely unchanged. This is true even if the initial volatile inventories of planets in the Trappist-1 system are highly correlated. The reason for this result is that b and c sit unambiguously interior to the runaway greenhouse limit, and so have potentially experienced ~8 Gyr of XUV-driven hydrodynamic escape; complete atmospheric erosion in this environment only weakly constrains stellar evolution and escape parameterizations. In contrast, e and f reside within the habitable zone, and likely experienced a comparatively short steam atmosphere during Trappist-1's pre-main sequence, and consequently complete atmospheric erosion remains unlikely across a broad swath of parameter space (e and f retain atmospheres in ~98% of model runs). Naturally, it is still possible that all Trappist-1 planets formed volatile-poor and are all airless today. But the airlessness of b (and c) does not require this, and as such, JWST transit spectroscopy of e and f remains the best near-term opportunity to characterize the atmospheres of habitable zone terrestrial planets.

Authors:S. Ulmer-Moll, H. P. Osborn, A. Tuson, J. A. Egger, M. Lendl, P. Maxted, A. Bekkelien, A. E. Simon, G. Olofsson, V. Adibekyan, Y. Alibert, A. Bonfanti, F. Bouchy, A. Brandeker, M. Fridlund, D. Gandolfi, C. Mordasini, C. M. Persson, S. Salmon, L. M. Serrano, S. G. Sousa, T. G. Wilson, M. Rieder, J. Hasiba, J. Asquier, D. Sicilia, I. Walter, R. Alonso, G. Anglada, D. Barrado y Navascues, S. C. C. Barros, W. Baumjohann, M. Beck, T. Beck, W. Benz, N. Billot, X. Bonfils, L. Borsato, C. Broeg, T. Bárczy, J. Cabrera, S. Charnoz, M. Cointepas, A. Collier Cameron, Sz. Csizmadia, P. E. Cubillos, M. B. Davies, M. Deleuil, A. Deline, L. Delrez, O. D. S. Demangeon, B. -O. Demory, X. Dumusque, D. Ehrenreich, N. L. Eisner, A. Erikson, A. Fortier, L. Fossati, M. Gillon, N. Grieves, M. Güdel, J. Hagelberg, R. Helled, S. Hoyer, K. G. Isaak, L. L. Kiss, J. Laskar, A. Lecavelier des Etangs, C. Lovis, D. Magrin, V. Nascimbeni, J. Otegi, R. Ottensammer, I. Pagano, E. Pallé, G. Peter, G. Piotto, D. Pollacco, A. Psaridi, D. Queloz, R. Ragazzoni, N. Rando, H. Rauer, I. Ribas, N. C. Santos, G. Scandariato, A. M. S. Smith, M. Steller, G. M. Szabó, D. Ségransan, N. Thomas, S. Udry, V. Van Grootel, J. Venturini, N. A. Walton

Abstract: A large sample of long-period giant planets has been discovered thanks to long-term radial velocity surveys, but only a few dozen of these planets have a precise radius measurement. Transiting gas giants are crucial targets for the study of atmospheric composition across a wide range of equilibrium temperatures and for shedding light on the formation and evolution of planetary systems. Indeed, compared to hot Jupiters, the atmospheric properties and orbital parameters of cooler gas giants are unaltered by intense stellar irradiation and tidal effects. We identify long-period planets in the Transiting Exoplanet Survey Satellite (TESS) data as duo-transit events. To solve the orbital periods of TESS duo-transit candidates, we use the CHaracterising ExOPlanet Satellite (CHEOPS) to observe the highest-probability period aliases in order to discard or confirm a transit event at a given period. We also collect spectroscopic observations with CORALIE and HARPS in order to confirm the planetary nature and measure the mass of the candidates. We report the discovery of a warm transiting Neptune-mass planet orbiting TOI-5678. After four non-detections corresponding to possible periods, CHEOPS detected a transit event matching a unique period alias. Joint modeling reveals that TOI-5678 hosts a 47.73 day period planet. TOI-5678 b has a mass of 20 (+-4) Me and a radius of 4.91 (+-0.08 Re) . Using interior structure modeling, we find that TOI-5678 b is composed of a low-mass core surrounded by a large H/He layer with a mass of 3.2 (+1.7, -1.3) Me. TOI-5678 b is part of a growing sample of well-characterized transiting gas giants receiving moderate amounts of stellar insolation (11 Se). Precise density measurement gives us insight into their interior composition, and the objects orbiting bright stars are suitable targets to study the atmospheric composition of cooler gas giants.

Authors:M. Pinamonti, D. Barbato, A. Sozzetti, L. Affer, S. Benatti, K. Biazzo, A. Bignamini, F. Borsa, M. Damasso, S. Desidera, A. F. Lanza, J. Maldonado, L. Mancini, L. Naponiello, D. Nardiello, M. Rainer, L. Cabona, C. Knapic, G. Andreuzzi, R. Cosentino, A. Fiorenzano, A. Ghedina, A. Harutyunyan, V. Lorenzi, M. Pedani, R. Claudi, E. Covino, A. Maggio, G. Micela, E. Molinari, I. Pagano, G. Piotto, E. Poretti

Abstract: We present the results of a high-cadence and high-precision radial velocity (RV) monitoring of 3 late-type dwarf stars hosting long-period giants with well-measured orbits, in order to search for short-period sub-Neptunes (SN, $M \sin i < 30$ M$_\oplus$). Building on the results and expertise of our previous studies, we carry out combined fits of our HARPS-N data with literature RVs, using MCMC analyses and Gaussian Process regression. We then use the results of our survey to estimate the frequency of sub-Neptunes in systems hosting cold-Jupiters, $f(SN|CJ)$, and compare it with the frequency around field M-dwarfs, $f(SN)$. We identify a new short-period low-mass planet orbiting GJ 328, GJ 328\,c, with $P_c = 241.8^{+1.3}_{-1.7}$ d and $M_c \sin i = 21.4^{+ 3.4}_{- 3.2}$ M$_\oplus$. We moreover identify and model the chromospheric activity signals and rotation periods of GJ 649 and GJ 849, around which no additional planet is found. Then, taking into account also planetary system around the previosuly-analyzed low-mass star BD-11 4672, we derive an estimate of the frequencies of inner planets in such systems. In particular $f(SN|CJ) = 0.25^{+0.58}_{-0.07}$ for mini-Neptunes ($10$ M$_\oplus < M \sin i < 30$ M$_\oplus$, $P < 150$ d), marginally larger than $f(SN)$. For lower-mass planets ($M \sin i < 10$ M$_\oplus$) instead $f(SN|CJ) <0.69$, compatible with $f(SN)$. In light of the newly detected mini-Neptune, we find tentative evidence of a positive correlation between the presence of those planets and that of inner low-mass planets, $f(SN|CJ) > f(SN)$. This might indicate that cold Jupiters have an opposite influence in the formation of inner sub-Neptunes around late-type dwarfs as opposed to their solar-type counterparts, boosting the formation of mini-Neptunes instead of impeding it.

Authors:Y. G. C. Frensch, G. Lo Curto, F. Bouchy, M. Mayor, G. Hébrard, C. Lovis, C. Moutou, F. A. Pepe, D. Queloz, N. Santos, D. Segransan, S. Udry, N. Unger

Abstract: Our aim is to detect and characterise long-period companions around main sequence stars (spectral types late F to early M). We use the RV method to search for exoplanets around stars. The RV variations are measured with HARPS at the ESO 3.6 metre telescope. The true mass and inclination of our heavier companions are provided by astrometry, for which we use proper motions from Hipparcos and Gaia. Five Jupiter-mass exoplanets are reported to orbit HIP54597, BD-210397 (x2), HD74698, and HD94771 with 8.9 yr, 5.2 yr, 17.4 yr, 9.4 yr, and 5.9 yr orbits, and to have minimum masses of $2.01 \pm 0.03$, $0.7 \pm 0.1$, $2.4^{+1.5}_{-0.2}$, $0.40 \pm 0.06$, and $0.53 \pm 0.03 M_J$ respectively. HD74698 also hosts a highly irradiated Neptune in a 15 day orbit with a minimum mass of $0.07 \pm 0.01 M_J$. The mass of HIP54597 b can maximally increase by 10% - 30%, the minimum mass of HD74698 c is likely equal to its true mass, and BD-210397 c has a mass of $2.66^{+0.63}_{-0.32} M_J$. HD62364 hosts a brown dwarf with a true mass of $18.77^{+0.66}_{-0.63} M_J$ in an orbit of 14 yr. HD56380B, HD221638B, and HD33473C have minimum masses within the brown dwarf limits, in orbits of 8.9 yr, 16.6 yr, and 50 yr respectively; however, astrometric measurements reveal them to be stellar binaries, with masses of $375.3^{+8.6}_{-8.4}$, $110.0^{+3.9}_{-3.7}$, and $271.0^{+3.9}_{-3.8} M_J$. The orbits of the stellar binaries HD11938 and HD61383 are incomplete. The preliminary result for HD61383 is a 0.190 $M_{\odot}$ binary in a 39 yr orbit. The secondary of the binary system HD11938 has a mass of 0.33 $M_{\odot}$ - which is confirmed by a secondary peak in the CCF - and a preliminary period of 35 yr. The origin of the 3.0 yr RV signal of HD3964 is uncertain as it shows entanglement with the magnetic cycle of the star. We finally report one more star, HD11608, with a magnetic cycle that mimics a planetary signal.

Authors:Hugh P. Osborn, Grzegorz Nowak, Guillaume Hébrard, Thomas Masseron, J. Lillo-Box, Enric Pallé, Anja Bekkelien, Hans-Gustav Florén, Pascal Guterman, Attila E. Simon, V. Adibekyan, Allyson Bieryla, Luca Borsato, Alexis Brandeker, David R. Ciardi, Andrew Collier Cameron, Karen A. Collins, Jo A. Egger, Davide Gandolfi, Matthew J. Hooton, David W. Latham, Monika Lendl, Elisabeth C. Matthews, Amy Tuson, Solène Ulmer-Moll, Andrew Vanderburg, Thomas G. Wilson, Carl Ziegler, Yann Alibert, Roi Alonso, Guillem Anglada, Luc Arnold, Joel Asquier, David Barrado y Navascues, Wolfgang Baumjohann, Thomas Beck, Alexandr A. Belinski, Willy Benz, Federico Biondi, Isabelle Boisse, Xavier Bonfils, Christopher Broeg, Lars A. Buchhave, Tamas Bárczy, S. C. C. Barros, Juan Cabrera, Carlos Cardona Guillen, Ilaria Carleo, Amadeo Castro-González, Sébastien Charnoz, Jessie Christiansen, Pia Cortes-Zuleta, Szilard Csizmadia, Shweta Dalal, Melvyn B. Davies, Magali Deleuil, Xavier Delfosse, Laetitia Delrez, Brice-Olivier Demory, Ava B. Dunlavey, David Ehrenreich, Anders Erikson, Rachel B. Fernandes, Andrea Fortier, Thierry Forveille, Luca Fossati, Malcolm Fridlund, Michaël Gillon, Robert F. Goeke, Maria V. Goliguzova, Erica J. Gonzales, M. N. Günther, Manuel Güdel, Neda Heidari, Christopher E. Henze, Steve Howell, Sergio Hoyer, Jonas Immanuel Frey, Kate G. Isaak, Jon M. Jenkins, Flavien Kiefer, Laszlo Kiss, Judith Korth, Pierre F. L. Maxted, Jacques Laskar, Alain Lecavelier des Etangs, Christophe Lovis, Michael B. Lund, Rafa Luque, Demetrio Magrin, Jose Manuel Almenara, Eder Martioli, Marko Mecina, Jennifer V. Medina, Daniel Moldovan, María Morales-Calderón, Giuseppe Morello, Claire Moutou, Felipe Murgas, Eric L. N. Jensen, Valerio Nascimbeni, Göran Olofsson, Roland Ottensamer, Isabella Pagano, Gisbert Peter, Giampaolo Piotto, Don Pollacco, Didier Queloz, Roberto Ragazzoni, Nicola Rando, Heike Rauer, Ignasi Ribas, George Ricker, Olivier D. S. Demangeon, Alexis M. S. Smith, Nuno Santos, Gaetano Scandariato, Sara Seager, Sergio G. Sousa, Manfred Steller, Gyula M. Szabó, Damien Ségransan, Nicolas Thomas, Stéphane Udry, Bernd Ulmer, Valerie Van Grootel, Roland Vanderspek, Nicholas Walton, Joshua N. Winn

Abstract: HIP 9618 (HD 12572, TOI-1471, TIC 306263608) is a bright ($G=9.0$ mag) solar analogue. TESS photometry revealed the star to have two candidate planets with radii of $3.9 \pm 0.044$ $R_\oplus$ (HIP 9618 b) and $3.343 \pm 0.039$ $R_\oplus$ (HIP 9618 c). While the 20.77291 day period of HIP 9618 b was measured unambiguously, HIP 9618 c showed only two transits separated by a 680-day gap in the time series, leaving many possibilities for the period. To solve this issue, CHEOPS performed targeted photometry of period aliases to attempt to recover the true period of planet c, and successfully determined the true period to be 52.56349 d. High-resolution spectroscopy with HARPS-N, SOPHIE and CAFE revealed a mass of $10.0 \pm 3.1 M_\oplus$ for HIP 9618 b, which, according to our interior structure models, corresponds to a $6.8\pm1.4\%$ gas fraction. HIP 9618 c appears to have a lower mass than HIP 9618 b, with a 3-sigma upper limit of $< 18M_\oplus$. Follow-up and archival RV measurements also reveal a clear long-term trend which, when combined with imaging and astrometric information, reveal a low-mass companion ($0.08^{+0.12}_{-0.05} M_\odot$) orbiting at $26^{+19}_{-11}$ au. This detection makes HIP 9618 one of only five bright ($K<8$ mag) transiting multi-planet systems known to host a planet with $P>50$ d, opening the door for the atmospheric characterisation of warm ($T_{\rm eq}<750$ K) sub-Neptunes.

Authors:Z. Garai, H. P. Osborn, D. Gandolfi, A. Brandeker, S. G. Sousa, M. Lendl, A. Bekkelien, C. Broeg, A. Collier Cameron, J. A. Egger, M. J. Hooton, Y. Alibert, L. Delrez, L. Fossati, S. Salmon, T. G. Wilson, A. Bonfanti, A. Tuson, S. Ulmer-Moll, L. M. Serrano, L. Borsato, R. Alonso, G. Anglada, J. Asquier, D. Barrado y Navascues, S. C. C. Barros, T. Bárczy, W. Baumjohann, M. Beck, T. Beck, W. Benz, N. Billot, F. Biondi, X. Bonfils, M. Buder, J. Cabrera, V. Cessa, S. Charnoz, Sz. Csizmadia, P. E. Cubillos, M. B. Davies, M. Deleuil, O. D. S. Demangeon, B. -O. Demory, D. Ehrenreich, A. Erikson, V. Van Eylen, A. Fortier, M. Fridlund, M. Gillon, V. Van Grootel, M. Güdel, M. N. Günther, S. Hoyer, K. G. Isaak, L. L. Kiss, M. H. Kristiansen, J. Laskar, A. Lecavelier des Etangs, C. Lovis, A. Luntzer, D. Magrin, P. F. L. Maxted, C. Mordasini, V. Nascimbeni, G. Olofsson, R. Ottensamer, I. Pagano, E. Pallé, G. Peter, G. Piotto, D. Pollacco, D. Queloz, R. Ragazzoni, N. Rando, H. Rauer, I. Ribas, N. C. Santos, G. Scandariato, D. Ségransan, A. E. Simon, A. M. S. Smith, M. Steller, Gy. M. Szabó, N. Thomas, S. Udry, J. Venturini, N. Walton

Abstract: Multi-planet systems are important sources of information regarding the evolution of planets. However, the long-period planets in these systems often escape detection. HD 22946 is a bright star around which 3 transiting planets were identified via TESS photometry, but the true orbital period of the outermost planet d was unknown until now. We aim to use CHEOPS to uncover the true orbital period of HD 22946d and to refine the orbital and planetary properties of the system, especially the radii of the planets. We used the available TESS photometry of HD 22946 and observed several transits of the planets b, c, and d using CHEOPS. We identified 2 transits of planet d in the TESS photometry, calculated the most probable period aliases based on these data, and then scheduled CHEOPS observations. The photometric data were supplemented with ESPRESSO radial velocity data. Finally, a combined model was fitted to the entire dataset. We successfully determined the true orbital period of the planet d to be 47.42489 $\pm$ 0.00011 d, and derived precise radii of the planets in the system, namely 1.362 $\pm$ 0.040 R$_\oplus$, 2.328 $\pm$ 0.039 R$_\oplus$, and 2.607 $\pm$ 0.060 R$_\oplus$ for planets b, c, and d, respectively. Due to the low number of radial velocities, we were only able to determine 3$\sigma$ upper limits for these respective planet masses, which are 13.71 M$_\oplus$, 9.72 M$_\oplus$, and 26.57 M$_\oplus$. We estimated that another 48 ESPRESSO radial velocities are needed to measure the predicted masses of all planets in HD 22946. Planet c appears to be a promising target for future atmospheric characterisation. We can also conclude that planet d, as a warm sub-Neptune, is very interesting because there are only a few similar confirmed exoplanets to date. Such objects are worth investigating in the near future, for example in terms of their composition and internal structure.

Authors:Jonathan Tennyson, Marco Pezzella, Jingxin Zhang, Sergei N. Yurchenko

Abstract: The ExoMol database currently provides comprehensive line lists for modelling the spectroscopic properties of molecules in hot atmospheres. Extending the spectral range of the data provided to ultraviolet (UV) wavelengths brings into play three processes not currently accounted for in the ExoMol data structure, namely photodissociation, which is an important chemical process in its own right,the opacity contribution due to continuum absorption and predissociation which can lead to significant and observable line broadening effects. Data structures are proposed which will allow these processes to be correctly captured and the (strong) temperature-dependent effects predicted for UV molecular photoabsorption in general and photodissociation in particular to be represented.

Authors:Amy Tuson, Didier Queloz, Hugh P. Osborn, Thomas G. Wilson, Matthew J. Hooton, Mathias Beck, Monika Lendl, Göran Olofsson, Andrea Fortier, Andrea Bonfanti, Alexis Brandeker, Lars A. Buchhave, Andrew Collier Cameron, David R. Ciardi, Karen A. Collins, Davide Gandolfi, Zoltan Garai, Steven Giacalone, João Gomes da Silva, Steve B. Howell, Jayshil A. Patel, Carina M. Persson, Luisa M. Serrano, Sérgio G. Sousa, Solène Ulmer-Moll, Andrew Vanderburg, Carl Ziegler, Yann Alibert, Roi Alonso, Guillem Anglada, Tamas Bárczy, David Barrado Navascues, Susana C. C. Barros, Wolfgang Baumjohann, Thomas Beck, Willy Benz, Nicolas Billot, Xavier Bonfils, Luca Borsato, Christopher Broeg, Juan Cabrera, Sébastien Charnoz, Dennis M. Conti, Szilard Csizmadia, Patricio E. Cubillos, Melvyn B. Davies, Magali Deleuil, Laetitia Delrez, Olivier D. S. Demangeon, Brice-Olivier Demory, Diana Dragomir, Courtney D. Dressing, David Ehrenreich, Anders Erikson, Zahra Essack, Jacopo Farinato, Luca Fossati, Malcolm Fridlund, Elise Furlan, Holden Gill, Michaël Gillon, Crystal L. Gnilka, Erica Gonzales, Manuel Güdel, Maximilian N. Günther, Sergio Hoyer, Kate G. Isaak, Jon M. Jenkins, Laszlo L. Kiss, Jacques Laskar, David W. Latham, Nicholas Law, Alain Lecavelier des Etangs, Gaspare Lo Curto, Christophe Lovis, Rafael Luque, Demetrio Magrin, Andrew W. Mann, Pierre F. L. Maxted, Michel Mayor, Scott McDermott, Marko Mecina, Christoph Mordasini, Annelies Mortier, Valerio Nascimbeni, Roland Ottensamer, Isabella Pagano, Enric Pallé, Gisbert Peter, Giampaolo Piotto, Don Pollacco, Tyler Pritchard, Roberto Ragazzoni, Nicola Rando, Francesco Ratti, Heike Rauer, Ignasi Ribas, George R. Ricker, Martin Rieder, Nuno C. Santos, Arjun B. Savel, Gaetano Scandariato, Richard P. Schwarz, Sara Seager, Damien Ségransan, Avi Shporer, Attila E. Simon, Alexis M. S. Smith, Manfred Steller, Chris Stockdale, Gyula M. Szabó, Nicolas Thomas, Guillermo Torres, René Tronsgaard, Stéphane Udry, Bernd Ulmer, Valérie Van Grootel, Roland Vanderspek, Julia Venturini, Nicholas A. Walton, Joshua N. Winn, Bill Wohler

Abstract: We report the discovery of two warm sub-Neptunes transiting the bright (G = 9.5 mag) K-dwarf HD 15906 (TOI 461, TIC 4646810). This star was observed by the Transiting Exoplanet Survey Satellite (TESS) in sectors 4 and 31, revealing two small transiting planets. The inner planet, HD 15906 b, was detected with an unambiguous period but the outer planet, HD 15906 c, showed only two transits separated by $\sim$ 734 days, leading to 36 possible values of its period. We performed follow-up observations with the CHaracterising ExOPlanet Satellite (CHEOPS) to confirm the true period of HD 15906 c and improve the radius precision of the two planets. From TESS, CHEOPS and additional ground-based photometry, we find that HD 15906 b has a radius of 2.24 $\pm$ 0.08 R$_\oplus$ and a period of 10.924709 $\pm$ 0.000032 days, whilst HD 15906 c has a radius of 2.93$^{+0.07}_{-0.06}$ R$_\oplus$ and a period of 21.583298$^{+0.000052}_{-0.000055}$ days. Assuming zero bond albedo and full day-night heat redistribution, the inner and outer planet have equilibrium temperatures of 668 $\pm$ 13 K and 532 $\pm$ 10 K, respectively. The HD 15906 system has become one of only six multiplanet systems with two warm ($\lesssim$ 700 K) sub-Neptune sized planets transiting a bright star (G $\leq$ 10 mag). It is an excellent target for detailed characterisation studies to constrain the composition of sub-Neptune planets and test theories of planet formation and evolution.

Authors:Alexandre C. M. Correia, Ema F. S. Valente

Abstract: We revisit the two body problem, where one body can be deformed under the action of tides raised by the companion. Tidal deformation and consequent dissipation result in spin and orbital evolution of the system. In general, the equations of motion are derived from the tidal potential developed in Fourier series expressed in terms of Keplerian elliptical elements, so that the variation of dissipation with amplitude and frequency can be examined. However, this method introduces multiple index summations and some orbital elements depend on the chosen frame, which is prone to confusion and errors. Here, we develop the quadrupole tidal potential solely in a series of Hansen coefficients, which are widely used in celestial mechanics and depend just on the eccentricity. We derive the secular equations of motion in a vectorial formalism, which is frame independent and valid for any rheological model. We provide expressions for a single average over the mean anomaly and for an additional average over the argument of the pericentre. These equations are suitable to model the long-term evolution of a large variety of systems and configurations, from planet satellite to stellar binaries. We also compute the tidal energy released inside the body for an arbitrary configuration of the system.

Authors:Manasvi Lingam, Amedeo Balbi, Swadesh M. Mahajan

Abstract: Photosynthesis is a plausible pathway for the sustenance of a substantial biosphere on an exoplanet. In fact, it is also anticipated to create distinctive biosignatures detectable by next-generation telescopes. In this work, we explore the excitation features of photopigments that harvest electromagnetic radiation by constructing a simple quantum-mechanical model. Our analysis suggests that the primary Earth-based photopigments for photosynthesis may not function efficiently at wavelengths $> 1.1$ $\mu$m. In the context of (hypothetical) extrasolar photopigments, we calculate the potential number of conjugated $\pi$-electrons ($N_\star$) in the relevant molecules, which can participate in the absorption of photons. By hypothesizing that the absorption maxima of photopigments are close to the peak spectral photon flux of the host star, we utilize the model to estimate $N_\star$. As per our formalism, $N_\star$ is modulated by the stellar temperature, and is conceivably higher (lower) for planets orbiting stars cooler (hotter) than the sun; exoplanets around late-type M-dwarfs might require an $N_\star$ twice that of the Earth. We conclude the analysis with a brief exposition of how our model could be empirically tested by future observations.

Authors:Denis E. Sergeev, Nathan J. Mayne, Thomas Bendall, Ian A. Boutle, Alex Brown, Iva Kavcic, James Kent, Krisztian Kohary, James Manners, Thomas Melvin, Enrico Olivier, Lokesh K. Ragta, Ben J. Shipway, Jon Wakelin, Nigel Wood, Mohamed Zerroukat

Abstract: We demonstrate that LFRic-Atmosphere, a model built using the Met Office's GungHo dynamical core, is able to reproduce idealised large-scale atmospheric circulation patterns specified by several widely-used benchmark recipes. This is motivated by the rapid rate of exoplanet discovery and the ever-growing need for numerical modelling and characterisation of their atmospheres. Here we present LFRic-Atmosphere's results for the idealised tests imitating circulation regimes commonly used in the exoplanet modelling community. The benchmarks include three analytic forcing cases: the standard Held-Suarez test, the Menou-Rauscher Earth-like test, and the Merlis-Schneider Tidally Locked Earth test. Qualitatively, LFRic-Atmosphere agrees well with other numerical models and shows excellent conservation properties in terms of total mass, angular momentum and kinetic energy. We then use LFRic-Atmosphere with a more realistic representation of physical processes (radiation, subgrid-scale mixing, convection, clouds) by configuring it for the four TRAPPIST-1 Habitable Atmosphere Intercomparison (THAI) scenarios. This is the first application of LFRic-Atmosphere to a possible climate of a confirmed terrestrial exoplanet. LFRic-Atmosphere reproduces the THAI scenarios within the spread of the existing models across a range of key climatic variables. Our work shows that LFRic-Atmosphere performs well in the seven benchmark tests for terrestrial atmospheres, justifying its use in future exoplanet climate studies.

Authors:Man-To Hui, Michael S. P. Kelley, Denise Hung, Tim Lister, Joseph Chatelain, Edward Gomez, Sarah Greenstreet

Abstract: Long-period comet C/2018 F4 (PANSTARRS) was observed to show duplicity of its inner region in 2020 September, suggestive of a splitting event. We here present analyses of our observations of the comet taken from the LOOK project and the University of Hawaii 2.2 m telescope after the discovery of the splitting. The two fragments Components A and B, estimated to be $\sim\!60$ m to 4 km in radius, remained highly similar to each other in terms of brightness, colour, and dust morphology throughout our observing campaign from 2020 September to 2021 December. Our fragmentation model yielded that the two components split at a relative speed of $3.00 \pm 0.18$ m s$^{-1}$ in 2020 late April, implying a specific energy change of $\left(5.3 \pm 2.8 \right) \times 10^3$ J kg$^{-1}$, and that Component B was subjected to a stronger nongravitational acceleration than Component A in both the radial and normal directions of the orbit. The obtained splitting time is broadly consistent with the result from the dust morphology analysis, which further suggested that the dominant dust grains were millimeter-sized and ejected at speed $\sim\!2$ m s$^{-1}$. We postulate that the pre-split nucleus of the comet consisted of two lobes resembling the one of 67P, or that the comet used to be a binary system like main-belt comet 288P. Regardless, we highlight the possibility of using observations of split comets as a feasible manner to study the bilobate shape or binarity fraction of cometary nuclei.

Authors:Harrison Nicholls, Eric Hébrard, Olivia Venot, Benjamin Drummond, Elise Evans

Abstract: The effect of enhanced UV irradiation associated with stellar flares on the atmospheric composition and temperature of gas giant exoplanets was investigated. This was done using a 1D radiative-convective-chemical model with self-consistent feedback between the temperature and the non-equilibrium chemistry. It was found that flare-driven changes to chemical composition and temperature give rise to prolonged trends in evolution across a broad range of pressure levels and species. Allowing feedback between chemistry and temperature plays an important role in establishing the quiescent structure of these atmospheres, and determines their evolution due to flares. It was found that cooler planets are more susceptible to flares than warmer ones, seeing larger changes in composition and temperature, and that temperature-chemistry feedback modifies their evolution. Long-term exposure to flares changes the transmission spectra of gas giant atmospheres; these changes differed when the temperature structure was allowed to evolve self-consistently with the chemistry. Changes in spectral features due to the effects of flares on these atmospheres can be associated with changes in composition. The effects of flares on the atmospheres of sufficiently cool planets will impact observations made with JWST. It is necessary to use self-consistent models of temperature and chemistry in order to accurately capture the effects of flares on features in the transmission spectra of cooler gas giants, but this depends heavily on the radiation environment of the planet.

Authors:Richard E. Zeebe

Abstract: Reliable studies of the long-term dynamics of planetary systems require numerical integrators that are accurate and fast. The challenge is often formidable because the chaotic nature of many systems requires relative numerical error bounds at or close to machine precision (~1e-16, double-precision arithmetic), otherwise numerical chaos may dominate over physical chaos. Currently, the speed/accuracy demands are usually only met by symplectic integrators. For example, the most up-to-date long-term astronomical solutions for the solar system in the past (widely used in, e.g., astrochronology and high-precision geological dating) have been obtained using symplectic integrators. Yet, the source codes of these integrators are unavailable. Here I present the symplectic integrator orbitN (lean version 1.0) with the primary goal of generating accurate and reproducible long-term orbital solutions for near-Keplerian planetary systems (here the solar system) with a dominant mass M0. Among other features, orbitN-1.0 includes M0's quadrupole moment, a lunar contribution, and post-Newtonian corrections (1PN) due to M0 (fast symplectic implementation). To reduce numerical roundoff errors, Kahan compensated summation was implemented. I use orbitN to provide insight into the effect of various processes on the long-term chaos in the solar system. Notably, 1PN corrections have the opposite effect on chaoticity/stability on 100-Myr vs. Gyr-time scale. For the current application, orbitN is about as fast or faster (factor 1.15-2.6) than comparable integrators, depending on hardware. The orbitN source code (C) is available at github.com/rezeebe/orbitN.

Authors:Isabella L. Trierweiler, Alexandra E. Doyle, Edward D. Young

Abstract: A persistent question in exoplanet demographics is whether exoplanetary systems form from similar compositional building blocks to our own. Polluted white dwarf stars offer a unique way to address this question as they provide measurements of the bulk compositions of exoplanetary material. We present a statistical analysis of the rocks polluting oxygen-bearing white dwarfs and compare their compositions to rocks in the Solar System. We find that the majority of the extrasolar rocks are consistent with the composition of typical chondrites. Measurement uncertainties prevent distinguishing between chondrites and bulk Earth, but do permit detecting the differences between chondritic compositions and basaltic or continental crust. We find no evidence of crust amongst the polluted white dwarfs. We show that the chondritic nature of extrasolar rocks is also supported by the compositions of local stars. While galactic chemical evolution results in variations in the relative abundances of rock-forming elements spatially and temporally on galaxy-wide scales, the current sample of polluted white dwarfs are sufficiently young and close to Earth that they are not affected by this process. We conclude that exotic compositions are not required to explain the majority of observed rock types around polluted white dwarfs, and that variations between exoplanetary compositions in the stellar neighborhood are generally not due to significant differences in the initial composition of protoplanetary disks. Nonetheless, there is evidence from stellar observations that planets formed in the first several billion years in the Galaxy have lower metal core fractions compared with Earth on average.

Authors:Philip T. Metzger, Kris Zacny, Phillip Morrison

Abstract: A physics-based computer model has been developed to support the development of volatile extraction from regolith of the Moon and asteroids. The model is based upon empirical data sets for extraterrestrial soils and simulants, including thermal conductivity of regolith and mixed composition ice, heat capacity of soil and mixed composition ice, hydrated mineral volatile release patterns, and sublimation of ice. A new thermal conductivity relationship is derived that generalizes cases of regolith with varying temperature, soil porosity, and pore vapor pressure. Ice composition is based upon measurements of icy ejecta from the Lunar CRater Observation and Sensing Satellite (LCROSS) impact and it is shown that thermal conductivity and heat capacity equations for water ice provide adequate accuracy at the present level of development. The heat diffusion equations are integrated with gas diffusion equations using multiple adaptive timesteps. The entire model is placed into a Crank-Nicholson framework where the finite difference formalism was extended to two dimensions in axisymmetry. The one-dimensional version of the model successfully predicts heat transfer that matches lunar and asteroid data sets. The axisymmetric model has been used to study heat dissipation around lunar drills and water extraction in asteroid coring devices.

Authors:Yuan-Zhe Dai, Hui-Gen Liu, Jia-Yi Yang, Ji-Lin Zhou

Abstract: Planets in young star clusters could shed light on planet formation and evolution since star clusters can provide accurate age estimation. However, the number of transiting planets detected in clusters was only $\sim 30$, too small for statistical analysis. Thanks to the unprecedented high-precision astrometric data provided by Gaia DR2 and Gaia DR3, many new Open Clusters(OCs) and comoving groups have been identified. The UPiC project aims to find observational evidence and interpret how planet form and evolve in cluster environments. In this work, we cross-match the stellar catalogs of new OCs and comoving groups with confirmed planets and candidates. We carefully remove false positives and obtain the biggest catalog of planets in star clusters up to now, which consists of 73 confirmed planets and 84 planet candidates. After age validation, we obtain the radius--age diagram of these planets/candidates. We find an increment of the fraction of Hot Jupiters(HJs) around 100 Myr and attribute the increment to the flyby-induced high-e migration in star clusters. An additional small bump of the fraction of HJs after 1 Gyr is detected, which indicates the formation timescale of HJ around field stars is much larger than that in star clusters. Thus, stellar environments play important roles in the formation of HJs. The hot-Neptune desert occurs around 100 Myr in our sample. A combination of photoevaporation and high-e migration may sculpt the hot-Neptune desert in clusters.

Authors:Alastair Claringbold, Paul Rimmer, Sarah Rugheimer, Oliver Shorttle

Abstract: The search for biosignatures on exoplanets connects the fields of biology and biochemistry to astronomical observation, with the hope that we might detect evidence of active biological processes on worlds outside the solar system. Here we focus on a complementary aspect of exoplanet characterisation connecting astronomy to prebiotic chemistry: the search for molecules associated with the origin of life, prebiosignatures. Prebiosignature surveys in planetary atmospheres offer the potential to both constrain the ubiquity of life in the galaxy and provide important tests of current prebiotic syntheses outside of the laboratory setting. Here, we quantify the minimum abundance of identified prebiosignature molecules that would be required for detection by transmission spectroscopy using JWST. We consider prebiosignatures on five classes of terrestrial planet: an ocean planet, a volcanic planet, a post-impact planet, a super-Earth, and an early Earth analogue. Using a novel modelling and detection test pipeline, with simulated JWST noise, we find the detection thresholds of hydrogen cyanide (HCN), hydrogen sulfide (H2S), cyanoacetylene (HC3N), ammonia (NH3), methane (CH4), acetylene (C2H2), sulfur dioxide (SO2), nitric oxide (NO), formaldehyde (CH2O), and carbon monoxide (CO) in a variety of low mean molecular weight (<5) atmospheres. We test the dependence of these detection thresholds on M dwarf target star and the number of observed transits, finding that a modest number of transits (1-10) are required to detect prebiosignatures in numerous candidate planets, including TRAPPIST-1e with a high mean molecular weight atmosphere. We find that the NIRSpec G395M/H instrument is best suited for detecting most prebiosignatures.

Authors:Emily Rauscher, Nicolas B. Cowan, Rodrigo Luger

Abstract: With JWST we can now characterize the atmospheres of planets on longer orbital planets, but this moves us into a regime where we cannot assume that tidal forces from the star have eroded planets' obliquities and synchronized their rotation rates. These rotation vectors may be tracers of formation and evolution histories and also enable a range of atmospheric circulation states. Here we delineate the orbital space over which tidal synchronization and alignment assumptions may no longer apply and present three-dimensional atmospheric models of a hypothetical warm Jupiter over a range of rotation rates and obliquities. We simulate the secondary eclipses of this planet for different possible viewing orientations and times during its orbital, seasonal cycle. We find that the eclipse depth can be strongly influenced by rotation rate and obliquity through the timing of the eclipse relative to the planet's seasonal cycle, and advise caution in attempting to derive properties such as albedo or day-night transport from this measurement. We predict that if warm Jupiters beyond the tidal limit have intrinsic diversity in their rotation vectors, then it will manifest itself as dispersion in their secondary eclipse depths. We explore eclipse mapping as a way to uniquely constrain the rotation vector of warm Jupiters but find that the associated signals are likely at the edge of JWST performance. Nevertheless, as JWST begins to measure the secondary eclipses of longer orbital period planets, we should expect to observe the consequences of a wider range of rotation states and circulation patterns.

Authors:Suman Saha

Abstract: The TESS follow-up of a large number of known transiting exoplanets provide unique opportunity to study their physical properties more precisely. Being a space-based telescope, the TESS observations are devoid of any noise component resulting from the interference of Earth's atmosphere. TESS also provides a better probability to observe subsequent transit events owing to its longer uninterrupted time-series observations compared to the ground-based telescopes. Especially, for the exoplanets around bright host-stars, TESS time-series observations provides high SNR lightcurves, which can be used for higher precision studies for these exoplanets. In this work, I have studied the TESS transit photometric follow-up observations of 28 exoplanets around bright stars with $V_{mag}\le$10. The already high SNR lightcurves from TESS have been further processed with a critical noise treatment algorithm, using the wavelet denoising and the Gaussian-process regression techniques, to effectively reduce the noise components both correlated and uncorrelated in time, which were then used to estimate the physical properties of these exoplanets. The study has resulted in very precise values for the physical properties of the target exoplanets, with the improvements in precision being significant for most of the cases compared to the previous studies. Also, since a comparatively large number of transit lightcurves from TESS observations were used to estimate these physical properties for each of the target exoplanets, which removes any bias due to the lack of sufficient datasets, these updated physical properties can be considered extremely accurate and reliable for future studies.

Authors:Marrick Braam, Paul I. Palmer, Leen Decin, Maureen Cohen, Nathan J. Mayne

Abstract: Determining the habitability and interpreting future atmospheric observations of exoplanets requires understanding the atmospheric dynamics and chemistry from a 3-D perspective. Previous studies have shown significant spatial variability in the ozone layer of synchronously rotating M-dwarf planets, assuming an Earth-like initial atmospheric composition. We use a 3-D Coupled Climate-Chemistry model to understand this distribution of ozone and identify the mechanism responsible for it. We document a previously unreported connection between the ozone production regions on the photochemically active dayside hemisphere and the nightside devoid of stellar radiation and thus photochemistry. We find that stratospheric dayside-to-nightside overturning circulation can advect ozone-rich air to the nightside. On the nightside, ozone-rich air subsides at the locations of two quasi-stationary Rossby gyres, resulting in an exchange between the stratosphere and troposphere and the accumulation of ozone at the gyre locations. We identify the hemispheric contrast in radiative heating and cooling as the main driver of this ozone circulation. Dynamically-driven chemistry also impacts other tracer species in the atmosphere (gaseous and non-gaseous phase) as long as chemical lifetimes exceed dynamical lifetimes. These findings illustrate the 3-D nature of planetary atmospheres, predicting spatial and temporal variability that will impact spectroscopic observations of exoplanet atmospheres.

Authors:Philip T. Metzger, Daniel T. Britt, Stephen D. Covey, John S. Lewis

Abstract: The first asteroid simulants workshop was held in late 2015. These materials are needed for tests of technologies and mission operational concepts, for training astronauts , for medical studies, and a variety of other purposes. The new program is based on lessons learned from the earlier lunar simulants program. It aims to deliver families of simulants for major spectral classes of asteroids both in cobble and regolith form, beginning with one type of carbonaceous chondrite and rapidly expanding to provide four to six more asteroid classes. These simulants will replicate a selected list of asteroid properties, but not all known properties, in order to serve the greatest number of users at an affordable price. They will be benchmarked by a variety of data sets including laboratory analysis of meteorites, observation of bolides, remote sensing of asteroids, data from asteroid missions, and scientific modeling. A variety of laboratory tests will verify the as-manufactured simulants are accurately and repeatedly providing the specified characteristics.

Authors:Kai Wu, M. B. N. Kouwenhoven, Rainer Spurzem, Xiaoying Pang

Abstract: Although debris disks may be common in exoplanet systems, only a few systems are known in which debris disks and planets coexist. Planets and the surrounding stellar population can have a significant impact on debris disk evolution. Here we study the dynamical evolution of debris structures around stars embedded in star clusters, aiming to determine how the presence of a planet affects the evolution of such structures. We combine NBODY6++GPU and REBOUND to carry out N-body simulations of planetary systems in star clusters (N=8000; Rh=0.78 pc) for a period of 100 Myr, in which 100 solar-type stars are assigned 200 test particles. Simulations are carried out with and without a Jupiter-mass planet at 50 au. We find that the planet destabilizes test particles and speeds up their evolution. The planet expels most particles in nearby and resonant orbits. Remaining test particles tend to retain small inclinations when the planet is present, and fewer test particles obtain retrograde orbits. Most escaping test particles with speeds smaller than the star cluster's escape speed originate from cold regions of the planetary system or from regions near the planet. We identify three regions within planetary systems in star clusters: (i) the private region of the planet, where few debris particles remain (40 - 60 au), (ii) the reach of the planet, in which particles are affected by the planet (0 - 400 au), and (iii) the territory of the planetary system, most particles outside which will eventually escape (0 - 700 au).

Authors:Rasmus Maråk, Emmanuel Blazquez, Pablo Gómez

Abstract: Proper modelling of the gravitational fields of irregularly shaped asteroids and comets is an essential yet challenging part of any spacecraft visit and flyby to these bodies. Accurate density representations provide crucial information for proximity missions which rely heavily on it to design safe and efficient trajectories. This work explores using a spacecraft swarm to maximise the measured gravitational signal in a hypothetical mission around the comet 67P/Churyumov-Gerasimenko. Spacecraft trajectories are simultaneously propagated with an evolutionary optimisation approach to maximise overall signal return. The propagation is based on an open-source polyhedral gravity model using a detailed mesh of 67P and considers the comet's sidereal rotation. We compare performance on a mission scenario using one and four spacecraft. The results show that the swarm achieved almost twice the single spacecraft coverage over a fixed mission duration. However, optimising for a single spacecraft results in a more effective trajectory. Overall, this work serves as a testbed for efficiently designing a set of trajectories in this complex gravitational environment balancing measured signals and risks in a swarm scenario. The codebase and results are publicly available at https://github.com/rasmusmarak/TOSS

Authors:A. Morbidelli, K. Batygin, E. Lega

Abstract: Context: Radius and mass measurements of short-period giant planets reveal that many of these planets contain a large amount of heavy elements, in sharp contrast with the expectations of the conventional core-accretion model for the origin of giant planets. Aims: The proposed explanations for the heavy-element enrichment of giant planets fall short of explaining the most enriched planets. We look for additional processes that can explain the full envelope of inferred enrichments. Methods: We revisit the dynamics of pebbles and dust in the vicinity of giant planets using analytic estimates. Although our results are derived in the framework of a viscous alpha-disk we also discuss the case of disks driven by angular momentum removal in magnetized winds. Results: When giant planets are far from the star, dust and pebbles are confined in a pressure bump at the outer edge of the planet-induced gap. Instead, when the planets reach the inner part of the disk (r << 2 au), dust penetrates the gap together with the gas. The dust/gas ratio can be enhanced by more than an order of magnitude if radial drift of dust is not impeded farther out by other barriers. Thus, hot planets undergoing runaway gas accretion can swallow a large amount of dust. Conclusions: Whereas the gas accreted by giant planets in the outer disk is very dust-poor, that accreted by hot planets can be extremely dust-rich. Thus, provided that a large fraction of the atmosphere of hot-Jupiters is accreted in situ, a large amount of dust can be accreted as well. We draw a distinction between this process and pebble accretion, which is ineffective at small stellocentric radii, even for super-Earths. Giant planets farther out in the disk are extremely effective barriers against the flow of pebbles and dust across their gap.

Authors:E. González-Álvarez, J. Kemmer, P. Chaturvedi, J. A. Caballero, A. Quirrenbach, P. J. Amado, V. J. S. Béjar, C. Cifuentes, E. Herrero, D. Kossakowski, A. Reiners, I. Ribas, E. Rodríguez, C. Rodríguez-López, J. Sanz-Forcada, Y. Shan, S. Stock, H. M. Tabernero, L. Tal-Or, M. R. Zapatero Osorio, A. P. Hatzes, Th. Henning, M. J. López-González, D. Montes, J. C. Morales, E. Pallé, S. Pedraz, M. Perger, S. Reffert, S. Sabotta, A. Schweitzer, M. Zechmeister

Abstract: We report the discovery of HN Lib b, a sub-Neptunian mass planet orbiting the nearby ($d \approx$ = 6.25 pc) M4.0 V star HN Lib detected by our CARMENES radial-velocity (RV) survey. We determined a planetary minimum mass of $M_\text{b}\sin i = $ 5.46 $\pm$ 0.75 $\text{M}_\oplus$ and an orbital period of $P_\text{b} = $ 36.116 $\pm$ 0.029 d, using $\sim$5 yr of CARMENES data, as well as archival RVs from HARPS and HIRES spanning more than 13 years. The flux received by the planet equals half the instellation on Earth, which places it in the middle of the conservative habitable zone (HZ) of its host star. The RV data show evidence for another planet candidate with $M_\text{[c]}\sin i = $ 9.7 $\pm$ 1.9 $\text{M}_\oplus$ and $P_\text{[c]} = $ 113.46 $\pm$ 0.20 d. The long-term stability of the signal and the fact that the best model for our data is a two-planet model with an independent activity component stand as strong arguments for establishing a planetary origin. However, we cannot rule out stellar activity due to its proximity to the rotation period of HN Lib, which we measured using CARMENES activity indicators and photometric data from a ground-based multi-site campaign as well as archival data. The discovery adds HN Lib b to the shortlist of super-Earth planets in the habitable zone of M dwarfs, but HN Lib [c] probably cannot be inhabited because, if confirmed, it would most likely be an icy giant.

Authors:Jonas Schuhmacher, Fabio Gratl, Dario Izzo, Pablo Gómez

Abstract: Recent advances in modeling density distributions, so-called neural density fields, can accurately describe the density distribution of celestial bodies without, e.g., requiring a shape model - properties of great advantage when designing trajectories close to these bodies. Previous work introduced this approach, but several open questions remained. This work investigates neural density fields and their relative errors in the context of robustness to external factors like noise or constraints during training, like the maximal available gravity signal strength due to a certain distance exemplified for 433 Eros and 67P/Churyumov-Gerasimenko. It is found that both models trained on a polyhedral and mascon ground truth perform similarly, indicating that the ground truth is not the accuracy bottleneck. The impact of solar radiation pressure on a typical probe affects training neglectable, with the relative error being of the same magnitude as without noise. However, limiting the precision of measurement data by applying Gaussian noise hurts the obtainable precision. Further, pretraining is shown as practical in order to speed up network training. Hence, this work demonstrates that training neural networks for the gravity inversion problem is appropriate as long as the gravity signal is distinguishable from noise. Code and results are available at https://github.com/gomezzz/geodesyNets

Authors:M. Gergacz, A. Kereszturi

Abstract: The search for ephemeral liquid water on Mars is an ongoing activity. After the recession of the seasonal polar ice cap on Mars, small water ice patches may be left behind in shady places due to the low thermal conductivity of the Martian surface and atmosphere. During late spring and early summer, these patches may be exposed to direct sunlight and warm up rapidly enough for the liquid phase to emerge. To see the spatial and temporal occurrence of such ice patches, optical images should be searched for and checked. Previously a manual image analysis was conducted on 110 images from the southern hemisphere, captured by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter space mission. Out of these, 37 images were identified with smaller ice patches, which were distinguishable by their brightness, colour and strong connection to local topographic shading. In this study, a convolutional neural network (CNN) is applied to find further images with potential water ice patches in the latitude band between -40{\deg} and -60{\deg}, where the seasonal retreat of the polar ice cap happens. Previously analysed HiRISE images are used to train the model, each was split into hundreds of pieces, expanding the training dataset to 6240 images. A test run conducted on 38 new HiRISE images indicates that the program can generally recognise small bright patches, however further training might be needed for more precise predictions.Using a CNN model may make it realistic to analyse all available surface images, aiding us in selecting areas for further investigation.

Authors:John E. Lane, Philip T. Metzger, Christopher D. Immer, Xiaoyi Li

Abstract: A mathematical model and software implementation developed to predict trajectories of single lunar dust particles acted on by a high velocity gas flow is discussed. The model uses output from a computation fluid dynamics (CFD) or direct simulation Monte Carlo (DSMC) simulation of a rocket nozzle hot gas jet. The gas density, velocity vector field, and temperature predicted by the CFD/DSMC simulations, provide the data necessary to compute the forces and accelerations acting on a single particle of regolith. All calculations of trajectory assume that the duration of particle flight is much shorter than the change in gas properties, i.e., the particle trajectory calculations take into account the spatial variation of the gas jet, but not the temporal variation. This is a reasonable first-order assumption. Final results are compared to photogrammetry derived estimates of dust angles form Apollo landing videos.

Authors:Jacob N. Gamsky, Philip T. Metzger

Abstract: The physical state of the lunar soil in the permanently shadowed craters of the moon is inferred from experimental investigation. The permanently shadowed craters do not undergo the same thermal cycling experienced by other parts of the moon and therefore could be slightly less compacted. This study is significant because excavating, roving, and landing interactions, along with the energy budgets and deployment schedules for associated technology, need to be scaled and designed properly. Results indicate that the degree of compaction due to thermal cycling is a function of the depth in the soil column.

Authors:G. L. Villanueva, H. B. Hammel, S. N. Milam, V. Kofman, S. Faggi, C. R. Glein, R. Cartwright, L. Roth, K. P. Hand, L. Paganini, J. Spencer, J. Stansberry, B. Holler, N. Rowe-Gurney, S. Protopapa, G. Strazzulla, G. Liuzzi, G. Cruz-Mermy, M. El Moutamid, M. Hedman, K. Denny

Abstract: Enceladus is a prime target in the search for life in our solar system, having an active plume likely connected to a large liquid water subsurface ocean. Using the sensitive NIRSpec instrument onboard JWST, we searched for organic compounds and characterized the plume's composition and structure. The observations directly sample the fluorescence emissions of H2O and reveal an extraordinarily extensive plume (up to 10,000 km or 40 Enceladus radii) at cryogenic temperatures (25 K) embedded in a large bath of emission originating from Enceladus' torus. Intriguingly, the observed outgassing rate (300 kg/s) is similar to that derived from close-up observations with Cassini 15 years ago, and the torus density is consistent with previous spatially unresolved measurements with Herschel 13 years ago, suggesting that the vigor of gas eruption from Enceladus has been relatively stable over decadal timescales. This level of activity is sufficient to maintain a derived column density of 4.5x1017 m-2 for the embedding equatorial torus, and establishes Enceladus as the prime source of water across the Saturnian system. We performed searches for several non-water gases (CO2, CO, CH4, C2H6, CH3OH), but none were identified in the spectra. On the surface of the trailing hemisphere, we observe strong H2O ice features, including its crystalline form, yet we do not recover CO2, CO nor NH3 ice signatures from these observations. As we prepare to send new spacecraft into the outer solar system, these observations demonstrate the unique ability of JWST in providing critical support to the exploration of distant icy bodies and cryovolcanic plumes.

Authors:Emese Kővári, Emese Forgács-Dajka, Tamás Kovács, Csaba Kiss, Zsolt Sándor

Abstract: On long enough timescales, chaotic diffusion has the potential to significantly alter the appearance of a dynamical system. The solar system is no exception: diffusive processes take part in the transportation of small bodies and provide dynamical pathways even for the distant trans-Neptunian objects to reach the inner solar system. In this Letter, we carry out a thorough investigation of the nature of chaotic diffusion. We analyze the temporal evolution of the mean squared displacement of ten thousand ensembles of test particles and quantify in each case the diffusion exponent (enabling the classification between normal, sub-, and super-diffusion), the generalized diffusion coefficient, and a characteristic diffusion timescale, too. This latter quantity is compared with an entropy-based timescale, and the two approaches are studied in light of direct computations as well. Our results are given in the context of two-dimensional maps, thereby facilitating the understanding of the relationship between the typical phase space structures and the properties of chaotic diffusion.

Authors:Hossein Fatheddin, Sedighe Sajadian

Abstract: It is plausible that most of the Stars in the Milky Way (MW) Galaxy, like the Sun, consist of planetary systems, instead of a single planet. Out of the estimately discovered 3,950 planet-hosting stars, about 860 of them are known to be multiplanetary systems (as of March, 2023). Gravitational microlensing, which is the magnification in the light of a source star, due to a single or several lenses, has proven to be one of the most useful Astrophysical phenomena with many applications. Until now, many extrasolar planets (exoplanets) have been discovered through binary microlensing, where the lens system consists of a star with one planet. In this paper, we discuss and explore the detection of multi-planetary systems that host two exoplanets via microlensing. This is done through the analysis and modeling of possible triple lens configurations (one star and two planets) of a microlensing event. Furthermore, we examine different magnifications and caustic areas of the second planet, by comparing the magnification maps of triple and binary models in different settings. We also discuss the possibility of detecting the corresponding light curves of such planetary systems with the future implementation of the Nancy Grace Roman (Roman) Space Telescope and its Galactic Time Domain survey.

Authors:Gayathri Viswanath, Markus Janson, Raffaele Gratton, Vito Squicciarini, Laetitia Rodet, Simon C. Ringqvist, Eric E. Mamajek, Sabine Reffert, Gaël Chauvin, Philippe Delorme, Arthur Vigan, Mickaël Bonnefoy, Natalia Engler, Silvano Desidera, Thomas Henning, Janis Hagelberg, Maud Langlois, Michael Meyer

Abstract: Recent observations from B-star Exoplanet Abundance Study (BEAST) have illustrated the existence of sub-stellar companions around very massive stars. In this paper, we present the detection of two lower mass companions to a relatively nearby ($148.7^{+1.5}_{-1.3}$ pc), young ($17^{+3}_{-4}$ Myr), bright (V=$6.632\pm0.006$ mag), $2.58\pm0.06~ M_{\odot}$ B9V star HIP 81208 residing in the Sco-Cen association, using the Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) instrument at the Very Large Telescope (VLT) in Chile. Analysis of the photometry obtained gives mass estimates of $67^{+6}_{-7}~M_J$ for the inner companion and $0.135^{+0.010}_{-0.013}~M_{\odot}$ for the outer companion, indicating the former to be most likely a brown dwarf and the latter to be a low-mass star. The system is compact but unusual, as the orbital planes of the two companions are likely close to orthogonal. The preliminary orbital solutions we derived for the system indicate that the star and the two companions are likely in a Kozai resonance, rendering the system dynamically very interesting for future studies.

Authors:S. T. Ogunjo, A. B. Rabiu

Abstract: Previous studies on the impact and influence of solar activity on terrestrial weather has yielded contradictory results in literature. Present study presents, on a global scale, the correlation between surface air temperature and two solar activity indices (Sunspot number, 'Rz', and solar radio flux at 10.7, 'F10.7' ) at different time scales during solar cycle 23. Global air temperature has higher correlation values of $\pm 0.8$ with F10.7 compared to Rz ($\pm 0.3$). Our results showed hemispheric delineation of the correlation between air temperature and solar activity with negative correlation in the southern hemisphere and positive correlation in the northern hemisphere. At the onset of the solar cycle, this hemispheric delineation pattern was prevalent, however, an inverse hemispheric delineation was observed at the recession of the solar cycle.

Authors:Yue Chen, Jian Li

Abstract: As the second part of our study, in this paper, we proceed to refine the solar system model by incorporating the gravitational influence of Plutinos in Neptune's 2:3 resonance. We aim to develop the arc model to represent the global perturbation of Plutinos by taking into account their asymmetric spatial distribution resulting from the 2:3 resonance, and demonstrate the difference to the commonly employed ring model. The global perturbation of Plutinos is measured by the change in the Sun-Neptune distance. We begin by deriving the number density of the discrete-arc comprised of point masses to accurately represent the continuous-arc. Based on the resonant characteristics of the 2:3 MMR, we then construct three overlapping discrete-arcs to model the Plutinos. The perturbations of these arcs are investigated in detail, considering various azimuthal and radial distributions associated with the resonant amplitudes A and eccentricities e of the Plutinos, respectively. The change in Sun-Neptune distance, i.e. $\Delta d_{SN}$, caused by Plutinos increases as the range of A widens. At e<=0.1, $\Delta d_{SN}$ can reach magnitudes on the order of 100 km. However, the effects of Plutinos' A and e can possibly balance each other. As given e>=0.25, we find that $\Delta d_{SN}$ approaches zero, indicating a negligible contribution from highly eccentric Plutinos to the planetary ephemerides. We finally provide a concise analytic expression, which contains the parameters A, e and the total mass of Plutinos, to estimate $\Delta d_{SN}$ at any epoch from 2020 to 2120. Furthermore, since the difference in $\Delta d_{SN}$ between the arc and ring model can be as large as 170 km, we conclude that the ring model is unsuitable for representing the perturbations of Plutinos. The idea of the multiple-arc model designed for Plutinos can be readily generalized to other MMRs heavily populated by small bodies.

Authors:Elyse Incha, Andrew Vanderburg, Tom Jacobs, Daryll LaCourse, Allyson Bieryla, Emily Pass, Steve B. Howell, Perry Berlind, Michael Calkins, Gilbert Esquerdo, David W. Latham, Andrew W. Mann

Abstract: The Kepler space telescope was responsible for the discovery of over 2,700 confirmed exoplanets, more than half of the total number of exoplanets known today. These discoveries took place during both Kepler's primary mission, when it spent 4 years staring at the same part of the sky, and its extended K2 mission, when a mechanical failure forced it to observe different parts of the sky along the ecliptic. At the very end of the mission, when Kepler was exhausting the last of its fuel reserves, it collected a short set of observations known as K2 Campaign 19. So far, no planets have been discovered in this dataset because it only yielded about a week of high-quality data. Here, we report some of the last planet discoveries made by Kepler in the Campaign 19 dataset. We conducted a visual search of the week of high-quality Campaign 19 data and identified three possible planet transits. Each planet candidate was originally identified with only one recorded transit, from which we were able to estimate the planets' radii and estimate the semimajor axes and orbital periods. Analysis of lower-quality data collected after low fuel pressure caused the telescope's pointing precision to suffer revealed additional transits for two of these candidates, allowing us to statistically validate them as genuine exoplanets. We also tentatively confirm the transits of one planet with TESS. These discoveries demonstrate Kepler's exoplanet detection power, even when it was literally running on fumes.

Authors:H. J. Deeg, I. Y. Georgieva, G. Nowak, C. M. Persson, B. L. Cale, F. Murgas, E. Pallé, D. Godoy Rivera, F. Dai, D. R. Ciardi, J. M. Akana Murphy, P. G. Beck, C. J. Burke, J. Cabrera, I. Carleo, W. D. Cochran, K. A. Collins, Sz. Csizmadia, M. El Mufti, M. Fridlund, A. Fukui, D. Gandolfi, R. A. García, E. W. Guenther, P. Guerra, S. Grziwa, H. Isaacson, K. Isogai, J. M. Jenkins, P. Kábath, J. Korth, K. W. F. Lam, D. W. Latham, R. Luque, M. B. Lund, J. H. Livingston, S. Mathis, S. Mathur, N. Narita, J. Orell-Miquel, H. L. M. Osborne, H. Parviainen, P. P. Plavchan, S. Redfield, D. R. Rodriguez, R. P. Schwarz, S. Seager, A. M. S. Smith, V. Van Eylen, J. Van Zandt, J. N Winn, C. Ziegler

Abstract: TOI 1416 (BD+42 2504, HIP 70705) is a V=10 late G or early K-type dwarf star with transits detected by TESS. Radial velocities verify the presence of the transiting planet TOI-1416 b, with a period of 1.07d, a mass of $3.48 M_{Earth}$ and a radius of $1.62 R_{Earth}$, implying a slightly sub-Earth density of $4.50$ g cm$^{-3}$. The RV data also further indicate a tentative planet c with a period of 27.4 or 29.5 days, whose nature cannot be verified due to strong suspicions about contamination by a signal related to the Moon's synodic period of 29.53 days. The near-USP (Ultra Short Period) planet TOI-1416 b is a typical representative of a short-period and hot ($T_{eq} \approx$ 1570 K) super-Earth like planet. A planet model of an interior of molten magma containing a significant fraction of dissolved water provides a plausible explanation for its composition, and its atmosphere could be suitable for transmission spectroscopy with JWST. The position of TOI-1416 b within the radius-period distribution corroborates that USPs with periods of less than one day do not form any special group of planets. Rather, this implies that USPs belong to a continuous distribution of super-Earth like planets with periods ranging from the shortest known ones up to ~ 30 days, whose period-radius distribution is delimitated against larger radii by the Neptune desert and by the period-radius valley that separates super-Earths from sub-Neptune planets. In the abundance of small-short periodic planets against period, a plateau between periods of 0.6 to 1.4 days has however become notable that is compatible with the low-eccentricity formation channel. For the Neptune desert, its lower limits required a revision due to the increasing population of short period planets and new limits are provided. These limits are also given in terms of the planets' insolation and effective temperatures.

Authors:K. L. Luhman, P. Tremblin, S. M. Birkmann, E. Manjavacas, J. Valenti, C. Alves de Oliveira, T. L. Beck, G. Giardino, N. Lutzgendorf, B. J. Rauscher, M. Sirianni

Abstract: We present 1-5um spectroscopy of the young planetary mass companion TWA 27B (2M1207B) performed with NIRSpec on board the James Webb Space Telescope. In these data, the fundamental band of CH_4 is absent and the fundamental band of CO is weak. The nondetection of CH_4 reinforces a previously observed trend of weaker CH_4 with younger ages among L dwarfs, which has been attributed to enhanced non-equilibrium chemistry among young objects. The weakness of CO may reflect an additional atmospheric property that varies with age, such as the temperature gradient or cloud thickness. We are able to reproduce the broad shape of the spectrum with an ATMO cloudless model that has T=1300 K, non-equilibrium chemistry, and a temperature gradient reduction caused by fingering convection. However, the fundamental bands of CH_4 and CO are somewhat stronger in the model. In addition, the model temperature of 1300 K is higher than expected from evolutionary models given the luminosity and age of TWA 27B (T=1200 K). Previous models of young L-type objects suggest that the inclusion of clouds could potentially resolve these issues; it remains to be seen whether cloudy models can provide a good fit to the 1-5um data from NIRSpec. TWA 27B exhibits emission in Paschen transitions and the He I triplet at 1.083um, which are signatures of accretion that provide the first evidence of a circumstellar disk. We have used the NIRSpec data to estimate the bolometric luminosity of TWA 27B (log L/L_sun=-4.466+/-0.014), which implies a mass of 5-6 MJup according to evolutionary models.

Authors:Richard B. Firestone

Abstract: Three major planets, Venus, Earth, and Mercury formed out of the solar nebula. A fourth planetesimal, Theia, also formed near Earth where it collided in a giant impact, rebounding as the planet Mars. During this impact Earth lost ${\approx}4$\% of its crust and mantle that is now is found on Mars and the Moon. At the antipode of the giant impact, $\approx$60\% of Earth's crust, atmosphere, and a large amount of mantle were ejected into space forming the Moon. The lost crust never reformed and became the Earth's ocean basins. The Theia impact site corresponds to Indian Ocean gravitational anomaly on Earth and the Hellas basin on Mars. The dynamics of the giant impact are consistent with the rotational rates and axial tilts of both Earth and Mars. The giant impact removed sufficient CO$_2$ from Earth's atmosphere to avoid a runaway greenhouse effect, initiated plate tectonics, and gave life time to form near geothermal vents at the continental margins. Mercury formed near Venus where on a close approach it was slingshot into the Sun's convective zone losing 94\% of its mass, much of which remains there today. Black carbon, from CO$_2$ decomposed by the intense heat, is still found on the surface of Mercury. Arriving at 616 km/s, Mercury dramatically altered the Sun's rotational energy, explaining both its anomalously slow rotation rate and axial tilt. These results are quantitatively supported by mass balances, the current locations of the terrestrial planets, and the orientations of their major orbital axes.

Authors:U. Lebreuilly, M. -M. Mac Low, B. Commerçon, D. S. Ebel

Abstract: Context: Chondrules originate from the reprocessing of dust grains. They are key building blocks of telluric planets, yet their formation, which must happen in strongly localized regions of high temperature, remains poorly understood. Aims: We examine the dust spatial distribution near regions of strong local heating produced by current sheets, as a step toward exploring a potential path for chondrule formation. We further aim to investigate current sheet formation under various conditions in protoplanetary disks in the presence of ambipolar diffusion and Ohmic resistivity and the effect of current sheet morphology on dust dynamics in their vicinity. Methods: We use the RAMSES code including modules for non-ideal magnetohydrodynamics and solution of the dynamics of multiple sizes of dust grains to compute unstratified shearing box simulations of current sheet formation. We investigate, through seven models the effect of the ambipolar diffusion and Ohmic resistivity strength, the initial density, and magnetic field, as well as the resolution and box size. Results: We find that current sheets form in all our models, with typical widths of 0.001-0.01 AU and that strong dust fraction variations occur for millimeter-sized grains. These variations are typically of an order of magnitude and up to two orders of magnitude for the most favorable cases. We also show that the box size and resolution has a strong impact on the current sheet distribution and intensity. Conclusions: The formation of current sheets that can intensely heat their surroundings near strong dynamical dust fraction variations could have important implications for chondrule formation, as it appears likely to happen in regions of large dust fraction.

Authors:Jake Taylor, Michael Radica, Luis Welbanks, Ryan J. MacDonald, Jasmina Blecic, Maria Zamyatina, Alexander Roth, Jacob L. Bean, Vivien Parmentier, Louis-Philippe Coulombe, Adina D. Feinstein, Néstor Espinoza, Björn Benneke, David Lafrenière, René Doyon, Eva-Maria Ahrer

Abstract: The newly operational JWST offers the potential to study the atmospheres of distant worlds with precision that has not been achieved before. One of the first exoplanets observed by JWST in the summer of 2022 was WASP-96 b, a hot-Saturn orbiting a G8 star. As part of the Early Release Observations program, one transit of WASP-96 b was observed with NIRISS/SOSS to capture its transmission spectrum from 0.6-2.85 microns. In this work, we utilise four retrieval frameworks to report precise and robust measurements of WASP-96 b's atmospheric composition. We constrain the logarithmic volume mixing ratios of multiple chemical species in its atmosphere, including: H$_2$O = $-3.59 ^{+ 0.35 }_{- 0.35 }$, CO$_2$ = $-4.38 ^{+ 0.47 }_{- 0.57 }$ and K = $-8.04 ^{+ 1.22 }_{- 1.71 }$. Notably, our results offer a first abundance constraint on potassium in WASP-96 b's atmosphere, and important inferences on carbon-bearing species such as CO$_2$ and CO. Our short wavelength NIRISS/SOSS data are best explained by the presence of an enhanced Rayleigh scattering slope, despite previous inferences of a clear atmosphere - although we find no evidence for a grey cloud deck. Finally, we explore the data resolution required to appropriately interpret observations using NIRISS/SOSS. We find that our inferences are robust against different binning schemes. That is, from low $R = 125$ to the native resolution of the instrument, the bulk atmospheric properties of the planet are consistent. Our systematic analysis of these exquisite observations demonstrates the power of NIRISS/SOSS to detect and constrain multiple molecular and atomic species in the atmospheres of hot giant planets.

Authors:Nicolas Kaufmann, Yann Alibert

Abstract: Context. The effects of planetesimal fragmentation on planet formation has been studied by various models on single embryos therefore neglecting concurrent effects mostly in the outer disk. They show that planetesimal fragmentation can both hinder or aid planet formation due to the introduction of competing effects, namely speeding up accretion and depleting the feeding zone of forming planets. Aims. We investigate the influence of the collisional fragmentation of planetesimals on the planet formation process using a population synthesis approach. We aim to investigate its effects for a large set of initial conditions and also explore the consequences on the formation of multiple embryos in the same disk. Methods. We run global planet formation simulations including fragmentation, drift and an improved ice line description. To do this we use a fragmentation model in our code. The initial conditions for the simulations that are informed by observations are varied to generate synthetic exoplanet populations. Results. Our synthetic populations show that depending on the typical size of solids generated in collisions, fragmentation in tandem with the radial drift can either enhance or hinder planet formation. For larger fragments we see increased accretion throughout the populations especially beyond the ice line. However, the shorter drift timescale of smaller fragments, due to their stronger coupling to the gas, can hinder the formation process. Furthermore, beyond the ice line fragmentation promotes late growth when the damping by gas drag fades Conclusions. Fragmentation significantly affects the planet formation process in various ways for all types of planet and warrants further investigation.

Authors:Michael Radica, Luis Welbanks, Néstor Espinoza, Jake Taylor, Louis-Philippe Coulombe, Adina D. Feinstein, Jayesh Goyal, Nicholas Scarsdale, Loic Albert, Priyanka Baghel, Jacob L. Bean, Jasmina Blecic, David Lafrenière, Ryan J. MacDonald, Maria Zamyatina, Romain Allart, Étienne Artigau, Natasha E. Batalha, Neil James Cook, Nicolas B. Cowan, Lisa Dang, René Doyon, Marylou Fournier-Tondreau, Doug Johnstone, Michael R. Line, Sarah E. Moran, Sagnick Mukherjee, Stefan Pelletier, Pierre-Alexis Roy, Geert Jan Talens, Joseph Filippazzo, Klaus Pontoppidan, Kevin Volk

Abstract: The future is now - after its long-awaited launch in December 2021, JWST began science operations in July 2022 and is already revolutionizing exoplanet astronomy. The Early Release Observations (ERO) program was designed to provide the first images and spectra from JWST, covering a multitude of science cases and using multiple modes of each on-board instrument. Here, we present transmission spectroscopy observations of the hot-Saturn WASP-96b with the Single Object Slitless Spectroscopy (SOSS) mode of the Near Infrared Imager and Slitless Spectrograph, observed as part of the ERO program. As the SOSS mode presents some unique data reduction challenges, we provide an in-depth walk-through of the major steps necessary for the reduction of SOSS data: including background subtraction, correction of 1/f noise, and treatment of the trace order overlap. We furthermore offer potential routes to correct for field star contamination, which can occur due to the SOSS mode's slitless nature. By comparing our extracted transmission spectrum with grids of atmosphere models, we find an atmosphere metallicity between 1x and 5x solar, and a solar carbon-to-oxygen ratio. Moreover, our models indicate that no grey cloud deck is required to fit WASP-96b's transmission spectrum, but find evidence for a slope shortward of 0.9$\mu$m, which could either be caused by enhanced Rayleigh scattering or the red wing of a pressure-broadened Na feature. Our work demonstrates the unique capabilities of the SOSS mode for exoplanet transmission spectroscopy and presents a step-by-step reduction guide for this new and exciting instrument.

Authors:Sheila Sagear, Sarah Ballard

Abstract: We investigate the underlying distribution of orbital eccentricities for planets around early-to-mid M dwarf host stars. We employ a sample of 163 planets around early- to mid-M dwarfs across 101 systems detected by NASA's Kepler Mission. We constrain the orbital eccentricity for each planet by leveraging the Kepler lightcurve together with a stellar density prior, constructed using metallicity from spectroscopy, Ks magnitude from 2MASS, and stellar parallax from Gaia. Within a Bayesian hierarchical framework, we extract the underlying eccentricity distribution, assuming alternately Rayleigh, half-Gaussian, and Beta functions for both single- and multi-transit systems. We describe the eccentricity distribution for apparently single-transiting planetary systems with a Rayleigh distribution with sigma = 0.19 (+0.04, -0.03), and for multi-transit systems with sigma = 0.03 (+0.02, -0.01). The data suggest the possibility of distinct dynamically warmer and cooler sub-populations within the single-transit distribution: The single-transit data prefer a mixture model composed of two distinct Rayleigh distributions with sigma_1 = 0.02 (+0.11, -0.00) and sigma_2 = 0.24 (+0.20, -0.03) over a single Rayleigh distribution, with 7:1 odds. We contextualize our findings within a planet formation framework, by comparing them to analogous results in the literature for planets orbiting FGK stars. By combining our derived eccentricity distribution with other M dwarf demographic constraints, we estimate the underlying eccentricity distribution for the population of early- to mid-M dwarf planets in the local neighborhood.

Authors:Siddharth Gandhi, Aurora Kesseli, Yapeng Zhang, Amy Louca, Ignas Snellen, Matteo Brogi, Yamila Miguel, Núria Casasayas-Barris, Stefan Pelletier, Rico Landman, Cathal Maguire, Neale P. Gibson

Abstract: Ground-based high-resolution spectroscopy (HRS) has detected numerous chemical species and atmospheric dynamics in exoplanets, most notably ultra-hot Jupiters (UHJs). However, quantitative estimates on abundances have been challenging but are essential for accurate comparative characterisation and to determine formation scenarios. In this work we retrieve the atmospheres of six UHJs (WASP-76~b, MASCARA-4~b, MASCARA-2~b, WASP-121~b, HAT-P-70~b and WASP-189~b) with ESPRESSO and HARPS-N/HARPS observations, exploring trends in eleven neutral species and dynamics. While Fe abundances agree well with stellar values, Mg, Ni, Cr, Mn and V show more variation, highlighting the difficulty in using a single species as a proxy for metallicity. We find that Ca, Na, Ti and TiO are under-abundant, potentially due to ionisation and/or night-side rain-out. Our retrievals also show that relative abundances between species are more robust, consistent with previous works. We perform spatially- and phase-resolved retrievals for WASP-76~b and WASP-121~b given their high signal-to-noise observations, and find the chemical abundances in each of the terminator regions are broadly consistent. We additionally constrain dynamics for our sample through Doppler shifts and broadening of the planetary signals during the primary eclipse, with median blue shifts between $\sim$0.9-9.0~km/s due to day-night winds. Furthermore, we constrain spectroscopic masses for MASCARA-2~b and HAT-P-70~b consistent with their known upper limits, but we note that these may be biased due to degeneracies. This work highlights the importance of future HRS studies to further probe differences and trends between exoplanets.

Authors:G. I. Kokhirova, A. I. Zhonmuhammadi, U. H. Khamroev, T. J. Jopek

Abstract: The Virginid meteoroid streams produce a series of meteor showers active annually during February-May. A certain parent comet is not found but a related association of some showers with near-Earth asteroids was previously established and a cometary origin of these asteroids was suggested. We performed a new search for NEAs belonging to the Virginid asteroid-meteoroid complex. On the base of calculation of orbital evolution of a sample of NEAs and determination of theoretical features of related showers a search for observable active showers close to theoretically predicted ones was carried out. As a result, the predicted showers of 29 NEAs were identified with the showers of the Virginid complex. Revealed association points to a cometary nature of NEAs that are moving within the stream and may be considered as extinct fragments of a larger comet-progenitor of the Virginid asteroid-meteoroid complex.

Authors:Matthias Laeuter, Tobias Kramer, Martin Rubin, Kathrin Altwegg

Abstract: The relation between ice composition in the nucleus of comet 67P/Churyumov-Gerasimenko on the one hand and relative abundances of volatiles in the coma on the other hand is important for the interpretation of density measurements in the environment of the cometary nucleus. For the 2015 apparition, in situ measurements from the two ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) sensors COPS (COmet Pressure Sensor) and DFMS (Double Focusing Mass Spectrometer) determined gas densities at the spacecraft position for the 14 gas species H2O, CO2, CO, H2S, O2, C2H6, CH3OH, H2CO, CH4, NH3, HCN, C2H5OH, OCS, and CS2. We derive the spatial distribution of the gas emissions on the complex shape of the nucleus separately for 50 subintervals of the two-year mission time. The most active patches of gas emission are identified on the surface. We retrieve the relation between solar irradiation and observed emissions from these patches. The emission rates are compared to a minimal thermophysical model to infer the surface active fraction of H2O and CO2. We obtain characteristic differences in the ice composition close to the surface between the two hemispheres with a reduced abundance of CO2 ice on the northern hemisphere (locations with positive latitude). We do not see significant differences for the ice composition on the two lobes of 67P/C-G.

Authors:Robert F. Wilson, Thomas Barclay, Brian P. Powell, Joshua Schlieder, Christina Hedges, Benjamin T. Montet, Elisa Quintana, Iain McDonald, Matthew T. Penny, Nestor Espinoza, Eamonn Kerins

Abstract: The Nancy Grace Roman Space Telescope (Roman) is NASA's next astrophysics flagship mission, expected to launch in late 2026. As one of Roman's core community science surveys, the Galactic Bulge Time Domain Survey (GBTDS) will collect photometric and astrometric data for over 100 million stars in the Galactic bulge to search for microlensing planets. To assess the potential with which Roman can detect exoplanets via transit, we developed and conducted pixel-level simulations of transiting planets in the GBTDS. From these simulations, we predict that Roman will find between $\sim$60,000 and $\sim$200,000 transiting planets, over an order of magnitude more planets than are currently known. While the majority of these planets will be giants ($R_p>4R_\oplus$) on close-in orbits ($a<0.3$ au), the yield also includes between $\sim$7,000 and $\sim$12,000 small planets ($R_p<4 R_\oplus$). The yield for small planets depends sensitively on the observing cadence and season duration, with variations on the order of $\sim$10-20% for modest changes in either parameter, but is generally insensitive to the trade between surveyed area and cadence given constant slew/settle times. These predictions depend sensitively on the Milky Way's metallicity distribution function, highlighting an incredible opportunity to understand exoplanet demographics across a comprehensive set of stellar populations and Galactic environments.

Authors:Andrew Li

Abstract: Of the three space telescopes launched so far to survey transiting extrasolar planets, CoRoT is unique in that it was the only one with spectral resolution, allowing for an extraordinary opportunity to study the reflective properties of exoplanets at different wavelengths. In this work, I present a systematic lightcurve analysis of the white-light and chromatic CoRoT lightcurves of CoRoT-1 in order to search for the secondary eclipse and orbital phase variation of the transiting extrasolar planet CoRoT-1 b, as well at search for any chromatic difference in the aforementioned effects. I manage to detect a significant secondary eclipse in the white lightcurve, and detect the eclipse marginally in all three of the color channels. However I am only able to significantly detect the planetary phase variation in the red channel lightcurve. The retrieved secondary eclipse depth is higher in the blue and green channels compared to the white and red, suggesting that CoRoT-1 b has a higher geometric albedo at shorter wavelengths. I also attempt to detect the secondary eclipse using TESS, but show that the available volume and precision of the data is not high enough to allow detection of the secondary eclipse.

Authors:Zachary Murray

Abstract: Asteroid diameters are traditionally difficult to estimate. When a direct measurement of the diameter cannot be made through either occultation or direct radar observation, the most common method is to approximate the diameter from infrared observations. Once the diameter is known, a comparison with visible light observations can be used to find the visible geometric albedo of the body. One of the largest datasets of asteroid albedos comes from the NEOWISE mission, which measured asteroid albedos both in the visible and infrared. We model these albedos as a function of proper elements available from the Asteroid Families Portal using an ensemble of neural networks. We find that both the visible and infrared geometric albedos are significantly correlated with asteroid position in the belt and occur in both asteroid families and in the background belt. We find that the ensemble's prediction reduces the average error in albedo by about 37% compared to a model that simply adopts an average albedo, with no regard for the dynamical state of the body. We then use this model to predict albedos for the half million main belt asteroids with proper elements available in the Asteroid Families Portal and provide the results in a catalog. Finally, we show that several presently categorized asteroid families exist within much larger groups of asteroids of similar albedos - this may suggest that further improvements in family identification can be made.

Authors:Jiayin Dong, Songhu Wang, Malena Rice, George Zhou, Chelsea X. Huang, Rebekah I. Dawson, Gudmundur K. Stefánsson, Samuel Halverson, Shubham Kanodia, Suvrath Mahadevan, Michael W. McElwain, Jaime A. Alvarado-Montes, Joe P. Ninan, Paul Robertson, Arpita Roy, Christian Schwab, Sarah E. Logsdon, Ryan C. Terrien, Karen A. Collins, Gregor Srdoc, Ramotholo Sefako, Didier Laloum, David W. Latham, Allyson Bieryla, Paul A. Dalba, Diana Dragomir, Steven Villanueva Jr., Steve B. Howell, George R. Ricker, S. Seager, Joshua N. Winn, Jon M. Jenkins, Avi Shporer, David Rapetti

Abstract: Warm Jupiters are close-in giant planets with relatively large planet-star separations (i.e., $10< a/R_\star <100$). Given their weak tidal interactions with their host stars, measurements of stellar obliquity may be used to probe the initial obliquity distribution and dynamical history for close-in gas giants. Using spectroscopic observations, we confirm the planetary nature of TOI-1859b and determine the stellar obliquity of TOI-1859 to be $\lambda = 38.9^{+2.8}_{-2.7}\deg$ relative to its planetary companion using the Rossiter-McLaughlin effect. TOI-1859b is a 64-day warm Jupiter orbiting around a late-F dwarf and has an orbital eccentricity of $0.57^{+0.12}_{-0.16}$, inferred purely from transit light curves. The eccentric and misaligned orbit of TOI-1859b is likely an outcome of dynamical interactions, such as planet-planet scattering and planet-disk resonance crossing.

Authors:Jeremy L. Smallwood

Abstract: In light of the recent confirmation of an eccentric orbit giant planet, $\beta$ Pic c, I revisit the formation and evolution of the warped debris disc in the system. $\beta$ Pic c is interior to $\beta$ Pic b, and the debris disc is exterior to both planets. Previous $N$-body simulations have shown that $\beta$ Pic b is responsible for exciting the inclination of the debris disc. With hydrodynamical simulations, I model a protoplanetary gas disc misaligned with the planets. I find that the gas disc does not exhibit significant long lasting inclination excitation from the planets even for the observed disc size. The warp that is excited by the planets propagates through the entire disc with a timescale much less than the gas disc lifetime. Therefore, the observed warp in the debris disc must be produced after the gas disc has dispersed. With analytical secular theory calculations, I show that two secular resonances are exterior to $\beta$ Pic b, located at $\sim 20\, \rm au$ and $\sim 25\, \rm au$. This agrees with my $N$-body simulations that show that these secular resonances shape the inner edge of the $\beta$ Pic debris disc at a radius that agrees with observations.

Authors:Pavel Koten, Lukáš Shrbený, Pavel Spurný, Jiří Borovička, Rostislav Štork, Tomáš Henych, Vlastimil Vojáček, Jan Mánek

Abstract: A tau-Herculid meteor outburst or even a storm was predicted by several models to occur around 5~UT on 31~May, 2022 as a consequence of the break-up of comet 73P/Schwassmann-Wachmann 3 in 1995. The multi-instrument and multi-station experiment was carried-out within the Czech Republic to cover possible earlier activity of the shower between 21 and 1 UT on 30/31 May. Multi-station observations using video and photographic cameras were used for calculation of the atmospheric trajectories and heliocentric orbits of the meteors. Their arrival times are used for determination of the shower activity profile. Physical properties of the meteoroids are evaluated using various criteria based on meteor heights. Evolution of spectra of three meteors are studied as well. This annual but poor meteor shower was active for the whole night many hours before the predicted peak. A comparison with dynamical models shows that a mix of older material ejected after 1900 and fresh particles originating from the 1995 comet fragmentation event was observed. Radiant positions of both groups of meteors were identified and found to be in good agreement with simulated radiants. Meteoroids with masses between 10 mg and 10 kg were recorded. The mass distribution index was slightly higher than 2. A study of the physical properties shows that the tau-Herculid meteoroids belong to the most fragile particles observed ever, especially among higher masses of meteoroids. Exceptionally bright bolide observed during the dawn represents a challenge for the dynamical simulations as it is necessary to explain how to transfer a half metre body to the vicinity of the Earth at the same time as millimetre sized particles.

Authors:Thibault Cavalié, Jonathan Lunine, Olivier Mousis

Abstract: Jupiter's deep abundances help to constrain the formation history of the planet and the environment of the protoplanetary nebula. Juno recently measured Jupiter's deep oxygen abundance near the equator to be 2.2$_{-2.1}^{+3.9}$ times the protosolar value (2$\sigma$ uncertainties). Even if the nominal value is supersolar, subsolar abundances cannot be ruled out. Here we use a state-of-the-art one-dimensional thermochemical and diffusion model with updated chemistry to constrain the deep oxygen abundance with upper tropospheric CO observations. We find a value of 0.3$_{-0.2}^{+0.5}$ times the protosolar value. This result suggests that Jupiter could have a carbon-rich envelope that accreted in a region where the protosolar nebula was depleted in water. However, our model can also reproduce a solar/supersolar water abundance if vertical mixing is reduced in a radiative layer where the deep oxygen abundance is obtained. More precise measurements of the deep water abundance are needed to discriminate between these two scenarios and understand Jupiter's internal structure and evolution.

Authors:Cristian Giuppone, Adrián Rodríguez, Viviam Alencastro, Fernando Roig, Tabaré Gallardo

Abstract: Mean motion resonances (MMR) are a frequent phenomenon among extrasolar planetary systems. Current observations indicate that many systems have planets that are close to or inside the 2:1 MMR, when the orbital period of one of the planets is twice the other. Analytical models to describe this particular MMR can only be reduced to integrable approximations in a few specific cases. While there are successful approaches to the study of this MMR in the case of very elliptic and/or very inclined orbits using semi-analytical or semi-numerical methods, these may not be enough to completely understand the resonant dynamics. In this work, we propose to apply a well-established numerical method to assess the global portrait of the resonant dynamics, which consists in constructing dynamical maps. Combining these maps with the results from a semi-analytical method, helps to better understand the underlying dynamics of the 2:1 MMR, and to identify the behaviors that can be expected in different regions of the phase space and for different values of the model parameters. We verify that the family of stable resonant equilibria bifurcate from symmetric to asymmetric librations, depending on the mass ratio and eccentricities of the resonant planets pair. This introduces new structures in the phase space, that turns the classical V-shape of the MMR, in the semi-major axis vs. eccentricity space, into a sand clock shape. We construct dynamical maps for three extrasolar planetary systems, TOI-216, HD27894, and K2-24, and discuss their phase space structure and their stability in the light of the orbital fits available in the literature.

Authors:Jiayin Dong, Daniel Foreman-Mackey

Abstract: Stellar obliquity, the angle between a planet's orbital axis and its host star's spin axis, traces the formation and evolution of a planetary system. In transiting exoplanet observations, only the sky-projected stellar obliquity can be measured, but this can be de-projected using an estimate of the stellar obliquity. In this paper, we introduce a flexible, hierarchical Bayesian framework that can be used to infer the stellar obliquity distribution solely from sky-projected stellar obliquities, including stellar inclination measurements when available. We demonstrate that while a constraint on the stellar inclination is crucial for measuring the obliquity of an individual system, it is not required for robust determination of the population-level stellar obliquity distribution. In practice, the constraints on the stellar obliquity distribution are mainly driven by the sky-projected stellar obliquities. When applying the framework to all systems with measured sky-projected stellar obliquity, which are mostly Hot Jupiter systems, we find that the inferred population-level obliquity distribution is unimodal and peaked at zero degrees. The misaligned systems have nearly isotropic stellar obliquities with no strong clustering near 90 degrees. The diverse range of stellar obliquities prefers dynamic mechanisms, such as planet-planet scattering after a convergent disk migration, which could produce both prograde and retrograde orbits of close-in planets with no strong inclination concentrations other than 0 degrees.

Authors:Brandon Park Coy, Conor A. Nixon, Naomi Rowe-Gurney, Richard Achterberg, Nicholas A. Lombardo, Leigh N. Fletcher, Patrick Irwin

Abstract: In this work we present, for the first time, infrared spectra of Titan from the Spitzer Space Telescope ($2004-2009$). The data are from both the short wavelength-low resolution (SL, $5.13-14.29\mathrm{\mu m}, R\sim60-127$) and short wavelength-high resolution channels (SH, $9.89 - 19.51\mathrm{\mu m}, R\sim600$) showing the emissions of CH$_{4}$, C$_{2}$H$_{2}$, C$_{2}$H$_{4}$, C$_{2}$H$_{6}$, C$_{3}$H$_{4}$, C$_{3}$H$_{6}$, C$_{3}$H$_{8}$, C$_{4}$H$_{2}$, HCN, HC$_{3}$N, and CO$_{2}$. We compare the results obtained for Titan from Spitzer to those of the Cassini Composite Infrared Spectrometer (CIRS) for the same time period, focusing on the $16.35-19.35\mathrm{\mu m}$ wavelength range observed by the SH channel but impacted by higher noise levels in CIRS observations. We use the SH data to provide estimated haze extinction cross-sections for the $16.67-17.54\mathrm{\mu m}$ range that are missing in previous studies. We conclude by identifying spectral features in the $16.35-19.35\mathrm{\mu m}$ wavelength range, including two prominent emission features at 16.39 and $17.35\mathrm{\mu m}$, that could be analyzed further through upcoming James Webb Space Telescope Cycle 1 observations with the Mid-Infrared Instrument ($5.0-28.3\mathrm{\mu m}, R\sim1500-3500$). We also highlight gaps in current spectroscopic knowledge of molecular bands, including candidate trace species such as C$_{60}$ and detected trace species such as C$_{3}$H$_{6}$, that could be addressed by theoretical and laboratory study.

Authors:Maximilian Sommer

Abstract: The term `$\alpha$-meteoroid' was introduced to describe a group of micrometeoroids with certain dynamical properties, which -- alongside the group of the $\beta$-meteoroids -- had been identified by the first generation of reliable in-situ dust detectors in interplanetary space. In recent years, use of the term $\alpha$-meteoroid has become more frequent again, under a subtly but crucially altered definition. This work shall bring attention to the discrepancy between the term's original and newly established meaning, and spotlight the now-overlooked group of particles that the term used to describe. We review past and present pertinent literature around the term $\alpha$-meteoroid, and assess the dynamics of the originally referred-to particles with respect to possible sources, showing that their formation is the expected consequence of collisional grinding of the zodiacal cloud at short heliocentric distances. The abundance of the original $\alpha$-meteoroids, which are essentially `bound $\beta$-meteoroids', makes them relevant to all in-situ dust experiments in the inner solar system. Due to the change of the term's meaning, however, they are not considered by contemporary studies. The characterization of this particle population could elucidate the processing of the innermost zodiacal cloud, and should thus be objective of upcoming in-situ dust experiments. The attained ambiguity of the term $\alpha$-meteoroid is not easily resolved, warranting great care and clarity going forward.

Authors:G. F. Benedict, B. E. McArthur, E. P. Nelan, J. L. Bean

Abstract: We combine Hubble Space Telescope (HST) Fine Guidance Sensor, Hipparcos, and Gaia DR3 astrometric observations of the K0 V star 14 Her with the results of an analysis of extensive ground-based radial velocity data to determine perturbation orbits and masses for two previously known companions, 14 Her b and c. Radial velocities obtained with the Hobby-Eberly Telescope and from the literature now span over twenty five years. With these data we obtain improved RV orbital elements for both the inner companion, 14 Her b and the long-period outer companion, 14 Her c. We also find evidence of an additional RV signal with P $/sim$ 3789d. We then model astrometry from Hipparcos, HST, and Gaia with RV results to obtain system parallax and proper motion, perturbation periods, inclinations, and sizes due to 14 Her b and c. We find P_b = 1767.6 +/- 0.2 d, perturbation semi-major axis {\alpha}_b = 1.3 +/- 0.1 mas, and inclination i_b = 36 +/- 3 degrees, P_c = 52160 +/- 1028 d, perturbation semi-major axis {\alpha}_c = 10.3 +/- 0.7 mas, and inclination i_c = 82 +/- 14 degrees. In agreement with a past investigation, the 14 Her b, c orbits exhibit significant mutual inclination. Assuming a primary mass M = 0.98 +/- 0.04Msun, we obtain companion masses M_b = 8.5 +/- 1.0Mjup and M_c = 7.1 +/- 1.0Mjup.

Authors:Josef Durech, Josef Hanus

Abstract: Gaia Data Release 3 contains accurate photometric observations of more than 150,000 asteroids covering a time interval of 34 months. With a total of about 3,000,000 measurements, a typical number of observations per asteroid ranges from a few to several tens. We aimed to reconstruct the spin states and shapes of asteroids from this dataset. We computed the viewing and illumination geometry for each individual observation and used the light curve inversion method to find the best-fit asteroid model, which was parameterized by the sidereal rotation period, the spin axis direction, and a low-resolution convex shape. To find the best-fit model, we ran the inversion for tens of thousands of trial periods on interval 2-10,000 h, with tens of initial pole directions. To find the correct rotation period, we also used a triaxial ellipsoid model for the shape approximation. In most cases the number of data points was insufficient to uniquely determine the rotation period. However, for about 8600 asteroids we were able to determine the spin state uniquely together with a low-resolution convex shape model. This large sample of new asteroid models enables us to study the spin distribution in the asteroid population. The distribution of spins confirms previous findings that (i) small asteroids have poles clustered toward ecliptic poles, likely because of the YORP-induced spin evolution, (ii) asteroid migration due to the Yarkovsky effect depends on the spin orientation, and (iii) members of asteroid families have the sense of rotation correlated with their proper semimajor axis: over the age of the family, orbits of prograde rotators evolved, due to the Yarkovsky effect, to larger semimajor axes, while those of retrograde rotators drifted in the opposite direction.

Authors:Sam O. M. Wright, Stevanus K. Nugroho, Matteo Brogi, Neale P. Gibson, Ernst J. W. de Mooij, Ingo Waldmann, Jonathan Tennyson, Hajime Kawahara, Masayuki Kuzuhara, Teruyuki Hirano, Takayuki Kotani, Yui Kawashima, Kento Masuda, Jayne L. Birkby, Chris A. Watson, Motohide Tamura, Konstanze Zwintz, Hiroki Harakawa, Tomoyuki Kudo, Klaus Hodapp, Shane Jacobson, Mihoko Konishi, Takashi Kurokawa, Jun Nishikawa, Masashi Omiya, Takuma Serizawa, Akitoshi Ueda, Sébastien Vievard, Sergei N. Yurchenko

Abstract: Individual vibrational band spectroscopy presents an opportunity to examine exoplanet atmospheres in detail by distinguishing where the vibrational state populations of molecules differ from the current assumption of a Boltzmann distribution. Here, retrieving vibrational bands of OH in exoplanet atmospheres is explored using the hot Jupiter WASP-33b as an example. We simulate low-resolution spectroscopic data for observations with the JWST's NIRSpec instrument and use high resolution observational data obtained from the Subaru InfraRed Doppler instrument (IRD). Vibrational band-specific OH cross section sets are constructed and used in retrievals on the (simulated) low and (real) high resolution data. Low resolution observations are simulated for two WASP-33b emission scenarios: under the assumption of local thermal equilibrium (LTE) and a toy non-LTE model for vibrational excitation of selected bands. We show that mixing ratios for individual bands can be retrieved with sufficient precision to allow the vibrational population distributions of the forward models to be reconstructed. A simple fit for the Boltzmann distribution in the LTE case shows that the vibrational temperature is recoverable in this manner. For high resolution, cross-correlation applications, we apply the individual vibrational band analysis to an IRD spectrum of WASP-33b, applying an 'un-peeling' technique. Individual detection significances for the two strongest bands are shown to be in line with Boltzmann distributed vibrational state populations consistent with the effective temperature of the WASP-33b atmosphere reported previously. We show the viability of this approach for analysing the individual vibrational state populations behind observed and simulated spectra including reconstructing state population distributions.

Authors:Shunyuan Mao, Ruobing Dong, Lu Lu, Kwang Moo Yi, Sifan Wang, Paris Perdikaris

Abstract: We develop a tool, which we name Protoplanetary Disk Operator Network (PPDONet), that can predict the solution of disk-planet interactions in protoplanetary disks in real-time. We base our tool on Deep Operator Networks (DeepONets), a class of neural networks capable of learning non-linear operators to represent deterministic and stochastic differential equations. With PPDONet we map three scalar parameters in a disk-planet system -- the Shakura \& Sunyaev viscosity $\alpha$, the disk aspect ratio $h_\mathrm{0}$, and the planet-star mass ratio $q$ -- to steady-state solutions of the disk surface density, radial velocity, and azimuthal velocity. We demonstrate the accuracy of the PPDONet solutions using a comprehensive set of tests. Our tool is able to predict the outcome of disk-planet interaction for one system in less than a second on a laptop. A public implementation of PPDONet is available at \url{https://github.com/smao-astro/PPDONet}.

Authors:Jingxuan Yang, Patrick G. J. Irwin, Joanna K. Barstow

Abstract: Spectroscopic phase curves of transiting hot Jupiters are spectral measurements at multiple orbital phases, giving a set of disc-averaged spectra that probe multiple hemispheres. By fitting model phase curves to observations, we can constrain the atmospheric properties of hot Jupiters such as molecular abundance, aerosol distribution and thermal structure, which offer insights into their dynamics, chemistry, and formation. In this work, we propose a novel 2D temperature scheme consisting of a dayside and a nightside to retrieve information from near-infrared phase curves, and apply the scheme to phase curves of WASP-43b observed by HST/WFC3 and Spitzer/IRAC. In our scheme, temperature is constant on isobars on the nightside and varies with cos$^n$(longitude/$\epsilon$) on isobars on the dayside, where $n$ and $\epsilon$ are free parameters. We fit all orbital phases simultaneously using the radiative transfer code NEMESISPY coupled to a Bayesian inference code. We first validate the performance of our retrieval scheme with synthetic phase curves generated from a GCM, and find our 2D scheme can accurately retrieve the latitudinally-averaged thermal structure and constrain the abundance of H$_2$O and CH$_4$. We then apply our 2D scheme to the observed phase curves of WASP-43b and find: (1) the dayside temperature-pressure profiles do not vary strongly with longitude and are non-inverted; (2) the retrieved nightside temperatures are extremely low, suggesting significant nightside cloud coverage; (3) the H$_2$O volume mixing ratio is constrained to $5.6\times10^{-5}$--$4.0\times10^{-4}$, and we retrieve an upper bound for CH$_4$ at $\sim$10$^{-6}$.

Authors:Shubh Agrawal, Jean-Baptiste Ruffio, Quinn M. Konopacky, Bruce Macintosh, Dimitri Mawet, Eric L. Nielsen, Kielan K. W. Hoch, Michael C. Liu, Travis S. Barman, William Thompson, Alexandra Z. Greenbaum, Christian Marois, Jenny Patience

Abstract: While radial velocity surveys have demonstrated that the population of gas giants peaks around $3~\text{au}$, the most recent high-contrast imaging surveys have only been sensitive to planets beyond $\sim~10~\text{au}$. Sensitivity at small angular separations from stars is currently limited by the variability of the point spread function. We demonstrate how moderate-resolution integral field spectrographs can detect planets at smaller separations ($\lesssim~0.3$ arcseconds) by detecting the distinct spectral signature of planets compared to the host star. Using OSIRIS ($R$ $\approx$ 4000) at the W. M. Keck Observatory, we present the results of a planet search via this methodology around 20 young targets in the Ophiuchus and Taurus star-forming regions. We show that OSIRIS can outperform high-contrast coronagraphic instruments equipped with extreme adaptive optics and non-redundant masking in the $0.05-0.3$ arcsecond regime. As a proof of concept, we present the $34\sigma$ detection of a high-contrast M dwarf companion at $\approx0.1$" with a flux ratio of $\approx0.92\%$ around the field F2 star HD 148352. We developed an open-source Python package, breads, for the analysis of moderate-resolution integral field spectroscopy data in which the planet and the host star signal are jointly modeled. The diffracted starlight continuum is forward-modeled using a spline model, which removes the need for prior high-pass filtering or continuum normalization. The code allows for analytic marginalization of linear hyperparameters, simplifying posterior sampling of other parameters (e.g., radial velocity, effective temperature). This technique could prove very powerful when applied to integral field spectrographs like NIRSpec on the JWST and other upcoming first-light instruments on the future Extremely Large Telescopes.

Authors:Peng-cheng Cao, Qiong Liu, Neng-Hui Liao, Qian-cheng Yang, Dong Huang

Abstract: We have collected a catalog of 1095 debris disks with properties and classification (resolved, planet, gas) information. From the catalog, we defined a less biased sample with 612 objects and presented the distributions of their stellar and disk properties to search for correlations between disks and stars. We found debris disks were widely distributed from B to M-type stars while planets were mostly found around solar-type stars, gases were easier to detect around early-type stars and resolved disks were mostly distributed from A to G- type stars. The fractional luminosity dropped off with stellar age and planets were mostly found around old stars while gas-detected disks were much younger. The dust temperature of both one-belt systems and cold components in two-belt systems increased with distance while decreasing with stellar age. In addition, we defined a less biased planet sample with 211 stars with debris disks but no planets and 35 stars with debris disks and planets and found the stars with debris disks and planets had higher metallicities than stars with debris disks but no planets. Among the 35 stars with debris disks and planets, we found the stars with disks and cool Jupiters were widely distributed with age from 10 Myr to 10 Gyr and metallicity from -1.56 to 0.28 while the other three groups tended to be old (> 4Gyr) and metal-rich (> -0.3). Besides, the eccentricities of cool Jupiters are distributed from 0 to 0.932 wider than the other three types of planets (< 0.3).

Authors:Jegug Ih, Eliza M. -R. Kempton, Emily A. Whittaker, Madeline Lessard

Abstract: Recently, the first JWST measurement of thermal emission from a rocky exoplanet was reported. The inferred dayside brightness temperature of TRAPPIST-1 b at 15 $\mu$m is consistent with the planet having no atmosphere and therefore no mechanism by which to circulate heat to its nightside. In this Letter, we compare the measured secondary eclipse depth of TRAPPIST-1 b to predictions from a suite of self-consistent radiative-convective equilibrium models in order to quantify the maximum atmospheric thickness consistent with the observation. We find that plausible atmospheres (i.e., those that contain at least 100 ppm CO$_2$) with surface pressures greater than 0.01 bar (0.1 bar) are ruled out at 1$\sigma$ (3$\sigma$), regardless of the choice of background atmosphere. Thicker atmospheres of up to 10 bar (100 bar) at 1$\sigma$ (3$\sigma$) are only allowed if the atmosphere lacks any strong absorbers across the mid-IR wavelength range, a scenario that we deem unlikely. We additionally model the emission spectra for bare-rock planets of various compositions. We find that a variety of silicate surfaces match the measured eclipse depth to within 1$\sigma$, and the best-fit grey albedo is $0.02 \pm 0.11$. We conclude that planned secondary eclipse observations at 12.8 $\mu$m will serve to validate the high observed brightness temperature of TRAPPIST-1 b, but are unlikely to further distinguish among the consistent atmospheric and bare-rock scenarios.

Authors:G. Maciejewski, J. Golonka, W. Łoboda, J. Ohlert, M. Fernandez, F. Aceituno

Abstract: Hot Jupiters have been perceived as loners devoid of planetary companions in close orbital proximity. However, recent discoveries based on space-borne precise photometry have revealed that at least some fraction of giant planets coexists with low-mass planets in compact orbital architectures. We report detecting a 1.446-day transit-like signal in the photometric time series acquired with the Transiting Exoplanet Survey Satellite (TESS) for the WASP-84 system, which is known to contain a hot Jupiter on a circular 8.5-day orbit. The planet was validated based on TESS photometry, and its signal was distilled in radial velocity measurements. The joint analysis of photometric and Doppler data resulted in a multi-planetary model of the system. With a mass of $15\, M_{\oplus}$, radius of $2\, R_{\oplus}$, and orbital distance of 0.024 au, the new planet WASP-84 c was classified as a hot super-Earth with the equilibrium temperature of 1300 K. A growing number of companions to hot Jupiters indicates that a non-negligible part of them must have formed under a quiescent scenario such as disc migration or in-situ formation.

Authors:Dorian Demars Univ. Grenoble Alpes, CNRS, IPAG, F-38000 Grenoble, France, Mickael Bonnefoy Univ. Grenoble Alpes, CNRS, IPAG, F-38000 Grenoble, France, Catherine Dougados Univ. Grenoble Alpes, CNRS, IPAG, F-38000 Grenoble, France, Yuhiko Aoyama Institute for Advanced Study, Tsinghua University, Beijing, People's Republic of China Department of Astronomy, Tsinghua University, Beijing, People's Republic of China Department of Earth and Planetary Science, The University of Tokyo, Japan, Thanawuth Thanathibodee Department of Astronomy, University of Michigan, Ann Arbor, MI, USA Institute for Astrophysical Research and Department of Astronomy, Boston University, Boston, MA, USA, Gabriel-Dominique Marleau Fakultät für Physik, Universität Duisburg-Essen, Tübingen, Germany Physikalisches Institut, Universität Bern, Bern, Switzerland Max-Planck-Institut für Astronomie, Heidelberg, Germany, Pascal Tremblin Maison de la Simulation, CEA, CNRS, Univ. Paris-Sud, UVSQ, Université Paris-Saclay, Gif-sur-Yvette, France, Philippe Delorme Univ. Grenoble Alpes, CNRS, IPAG, F-38000 Grenoble, France, Paulina Palma-Bifani Université Côte d'Azur, OCA, Lagrange CNRS, Nice, France, Simon Petrus Instituto de Física y Astronomía, Facultad de Ciencias, Universidad de Valparaíso, Av. Gran Bretaña, Valparaíso, Chile Núcleo Milenio Formación Planetaria - NPF, Universidad de Valparaíso, Av., Valparaíso, Chile, Brendan P. Bowler Department of Astronomy, The University of Texas at Austin, Austin, TX, USA, Gael Chauvin Université Côte d'Azur, OCA, Lagrange CNRS, Nice, France Univ. Grenoble Alpes, CNRS, IPAG, F-38000 Grenoble, France, Anne-Marie Lagrange LESIA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, Univ. Paris Diderot, Sorbonne Paris Cité, Meudon, France Univ. Grenoble Alpes, CNRS, IPAG, F-38000 Grenoble, France

Abstract: Emission lines indicative of active accretion have been seen on a handful of low-mass companions (M < 30 MJup) to stars. Line variability is ubiquitous on stellar accretors but has never been characterized in detail on low-mass companions and can give insights on the accretion mechanism at play. We investigate the emission line variability of two low-mass companions (M<30 MJup) to stars to understand their accretion mechanisms. Using J-band observations, we analyze the short to long-term variability of the HI Paschen {\beta} emission line (1.282 {\mu}m) for GQ Lup b and GSC 06214-00210 b. Archival spectroscopic observations are also examined to extend the time span. We compare their line profiles and intensities to more massive accretors and magnetospheric accretion and shock models. Both objects have HI Paschen {\beta} flux variability that is moderate at short timescales (< 50 %) and increases at longer timescales (~1000 % on decade timescales), resembling classical T Tauri stars. GQ Lup b's line profiles are compatible with magnetospheric accretion. GSC 06214-00210 b's profiles are reproduced by both magnetospheric accretion and shock models, except for the brightest epoch for which the shock model is highly favored. Both companions have C/O values broadly consistent with solar values. While magnetospheric accretion is favored for GQ Lup b, higher resolution (R > 10000) observations are required to disentangle the two (non-exclusive) line formation mechanisms. The similarity in variability behavior may support similar accretion mechanisms between these low-mass companions and classical T Tauri stars. The significant variability observed at months and longer timescales could explain the low yield of H{\alpha} imaging campaigns.

Authors:Samuel W. Yee, Joshua N. Winn

Abstract: The probability that a Sun-like star has a close-orbiting giant planet (period < 1 year) increases with stellar metallicity. Previous work provided evidence that the period distribution of close-orbiting giant planets is also linked to metallicity, hinting that there two formation/evolution pathways for such objects, one of which is more probable in high-metallicity environments. Here, we check for differences in the period distribution of hot Jupiters (P < 10 days) as a function of host star metallicity, drawing on a sample of 232 transiting hot Jupiters and homogeneously-derived metallicities from Gaia Data Release 3. We found no evidence for any metallicity dependence; the period distributions of hot Jupiters around metal-poor and metal-rich stars are indistinguishable. As a byproduct of this study, we provide transformations between metallicities from the Gaia Radial Velocity Spectrograph and from traditional high-resolution optical spectroscopy of main-sequence FGK stars.

Authors:Prithivraj G, Alka Kumari

Abstract: NASA's Kepler Space Telescope has been instrumental in the task of finding the presence of exoplanets in our galaxy. This search has been supported by computational data analysis to identify exoplanets from the signals received by the Kepler telescope. In this paper, we consider building upon some existing work on exoplanet identification using residual networks for the data of the Kepler space telescope and its extended mission K2. This paper aims to explore how deep learning algorithms can help in classifying the presence of exoplanets with less amount of data in one case and a more extensive variety of data in another. In addition to the standard CNN-based method, we propose a Siamese architecture that is particularly useful in addressing classification in a low-data scenario. The CNN and ResNet algorithms achieved an average accuracy of 68% for three classes and 86% for two-class classification. However, for both the three and two classes, the Siamese algorithm achieved 99% accuracy.

Authors:Maria E. Steinrueck, Tommi Koskinen, Panayotis Lavvas, Vivien Parmentier, Sebastian Zieba, Xianyu Tan, Xi Zhang, Laura Kreidberg

Abstract: Photochemical hazes are expected to form in hot Jupiter atmospheres and may explain the strong scattering slopes and muted spectral features observed in the transmission spectra of many hot Jupiters. Absorption and scattering by photochemical hazes have the potential to drastically alter temperature structure and atmospheric circulation of these planets but have previously been neglected in general circulation models (GCMs). We present GCM simulations of hot Jupiter HD 189733b that include photochemical hazes as a radiatively active tracer fully coupled to atmospheric dynamics. The influence of haze radiative feedback strongly depends on the assumed haze optical properties. For soot hazes, two distinct thermal inversions form, separated by a local temperature minimum around 10$^{-5}$ bar caused by upwelling on the dayside mixing air with low haze abundance upwards. The equatorial jet broadens and slows down. The horizontal distribution of hazes remains relatively similar to simulations with radiatively passive tracers. For Titan-type hazes, the equatorial jet accelerates and extends to much lower pressures, resulting in a dramatically different 3D distribution of hazes compared to radiatively passive or soot hazes. Further experimental and observational studies to constrain the optical properties of photochemical hazes will therefore be crucial for understanding the role of hazes in exoplanet atmospheres. In the dayside emission spectrum, for both types of hazes the amplitude of near-infrared features is reduced, while the emitted flux at longer wavelengths ($>$4 $\mu$m) increases. Haze radiative feedback leads to increased phase curve amplitudes in many infrared wavelength regions, mostly due to stronger dayside emission.

Authors:Agnibha Banerjee, Joanna K. Barstow, Carole A. Haswell, Stephen R. Lewis

Abstract: Transmission spectroscopy is one of the most successful methods of learning about exoplanet atmospheres. The process of retrievals using transmission spectroscopy consists of creating numerous forward models and comparing them to observations to solve the inverse problem of constraining the atmospheric properties of exoplanets. We explore the impact of one simplifying assumption commonly employed by forward models of transiting exoplanets: namely that the planet can be treated as an isolated, non-rotating spherical body. The centrifugal acceleration due to a planet's rotation opposes the gravitational pull on a planet's atmosphere and increases its scale height. Conventional forward models used for retrievals generally do not include this effect. We find that atmospheric retrievals produce significantly different results for close-in planets with low gravity when this assumption is removed, e.g., differences between true and retrieved values of gas abundances greater than 1$\sigma$ for a simulated planet analogous to WASP-19 b. We recommend that the correction to the atmospheric scale height due to this effect be taken into account for the analysis of high precision transmission spectra of exoplanets in the future, most immediately JWST Cycle 1 targets WASP-19 b and WASP-121 b.

Authors:Marcus L. Marcussen, Simon H. Albrecht

Abstract: In this paper we report on the follow-up of five potential exoplanets detected with Gaia astrometry and provide an overview of what is currently known about the nature of the entire Gaia astrometric exoplanet candidate sample, 72 systems in total. We discuss the primary false-positive scenario for astrometric planet detections: binary systems with alike components that produce small photocenter motions, mimicking exoplanets. These false positives can be identified as double-lined SB2 binaries through analysis of high resolution spectra. Doing so we find that three systems, Gaia DR3 1916454200349735680, Gaia DR3 2052469973468984192, and Gaia DR3 5122670101678217728 are indeed near equal mass double star systems rather than exoplanetary systems. The spectra of the other two analyzed systems, HD 40503 and HIP 66074, are consistent with the exoplanet scenario in that no second set of lines can be found in the time series of publicly available high resolution spectra. However, their Gaia astrometric solutions imply radial-velocity semi-amplitudes $\sim$\,3 (HD 40503) and $\sim$\,15 (HIP 66074) larger than what was observed with ground based spectrographs. The Gaia astrometry orbital solutions and ground-based radial-velocity measurements exhibit inconsistencies in six out of a total of 12 exoplanet candidate systems where such data are available, primarily due to substantial differences between observed ground-based radial-velocity semi-amplitudes and those implied by the Gaia orbits. We investigated various hypotheses as to why this might be the case, and though we found no clear perpetrator, we note that a mismatch in orbital inclination offers the most straightforward explanation.

Authors:A. Chomez, A. -M. Lagrange, P. Delorme, M. Langlois, G. Chauvin, O. Flasseur, J. Dallant, F. Philipot, S. Bergeon, D. Albert, N. Meunier, P. Rubini

Abstract: We aim at searching for exoplanets on the whole ESO/VLT-SPHERE archive with improved and unsupervised data analysis algorithm that could allow to detect massive giant planets at 5 au. To prepare, test and optimize our approach, we gathered a sample of twenty four solar-type stars observed with SPHERE using angular and spectral differential imaging modes. We use PACO, a new generation algorithm recently developed, that has been shown to outperform classical methods. We also improve the SPHERE pre-reduction pipeline, and optimize the outputs of PACO to enhance the detection performance. We develop custom built spectral prior libraries to optimize the detection capability of the ASDI mode for both IRDIS and IFS. Compared to previous works conducted with more classical algorithms than PACO, the contrast limits we derived are more reliable and significantly better, especially at short angular separations where a gain by a factor ten is obtained between 0.2 and 0.5 arcsec. Under good observing conditions, planets down to 5 MJup, orbiting at 5 au could be detected around stars within 60 parsec. We identified two exoplanet candidates that require follow-up to test for common proper motion. In this work, we demonstrated on a small sample the benefits of PACO in terms of achievable contrast and of control of the confidence levels. Besides, we have developed custom tools to take full benefits of this algorithm and to quantity the total error budget on the estimated astrometry and photometry. This work paves the way towards an end-to-end, homogeneous, and unsupervised massive re-reduction of archival direct imaging surveys in the quest of new exoJupiters.

Authors:Zdenek Sekanina

Abstract: In the context of a recently proposed contact-binary model of the Kreutz system, all its members are products of the process of cascading fragmentation of the two lobes of the parent, Aristotle's comet of 372 BC. This process presumably began with the lobes' separation from each other near aphelion. However, not every object in a Kreutz-like orbit is a Kreutz sungrazer. Any surviving sungrazer that had split off from the progenitor before the lobes separated, as well as its surviving fragments born in any subsequent tidal or nontidal event, are by definition not members of the Kreutz system. Yet, as parts of the same progenitor, they belong -- as do all Kreutz sungrazers -- to a broader assemblage of related objects, which I refer to as a super-Kreutz system. After estimating the ratio of the number of super-Kreutz members to nonmembers among potential historical sungrazers, I generate representative extended pedigree charts for both the Kreutz system and super-Kreutz system. While the fragmentation paths and relationships among the individual sungrazers or potential sungrazers in the two charts are (with at most a few exceptions) arbitrary, the purpose of the exercise is to suggest that the Kreutz system proper could in effect represent an ultimate deagglomeration stage of the super-Kreutz system.

Authors:Sérgio R. A. Gomes, Alexandre C. M. Correia

Abstract: The orbits of the main satellites of Uranus are expected to slowly drift away owing to tides raised in the planet. As a result, the 5/3 mean motion resonance between Ariel and Umbriel was likely encountered in the past. Previous studies have shown that, in order to prevent entrapment in this resonance, the eccentricities of the satellites must be larger than $\sim 0.01$ at the epoch, which is hard to explain. On the other hand, if the satellites experience some temporary capture and then escape, the inclinations rise to high values that are not observed today. We have revisited this problem both analytically and numerically focussing on the inclination, using a secular two-satellite model with circular orbits. We show that if the inclination of Umbriel was around $0.15^{\circ}$ at the time of the 5/3 resonance encounter, capture can be avoided in about $60\%$ of the cases. Moreover, after the resonance crossing, the inclination of Umbriel drops to a mean value around $0.08^{\circ}$, which is close to the presently observed one. The final inclination of Ariel is distributed between $0.01^{\circ}$ and $0.25^{\circ}$ with a nearly equal probability, which includes the present mean value of $0.02^{\circ}$.

Authors:Julio C. Sanchez, Hanspeter Schaub

Abstract: This manuscript develops a simultaneous navigation and gravity estimation strategy around a small body. The scheme combines dynamical model compensation with a mascon gravity fit. Dynamical compensation adds the unmodeled acceleration to the filter state. Consequently, the navigation filter is able to generate an on-orbit position-unmodeled acceleration dataset. The available measurements correspond to the landmarks-based navigation technique. Accordingly, an on-board camera is able to provide landmark pixels. The aforementioned position-unmodeled acceleration dataset serves to train a mascon gravity model on-board while in flight. The training algorithm finds the optimal mass values and locations using Adam gradient descent. By a careful choice of the mascon variables and constraints projection, the masses are ensured to be positive and within the small body shape. The numerical results provide a comprehensive analysis on the global gravity accuracy for different estimation scenarios.

Authors:Isabel Rebollido, Sebastian Zieba, Daniela Iglesias, Vincent Bourrier, Flavien Kiefer, Alain Lecavelier Des Etangs

Abstract: The presence of minor bodies in exoplanetary systems is in most cases inferred through infra-red excesses, with the exception of exocomets. Even if over 35 years have passed since the first detection of exocomets around beta Pic, only ~ 25 systems are known to show evidence of evaporating bodies, and most of them have only been observed in spectroscopy. With the appearance of new high-precision photometric missions designed to search for exoplanets, such as CHEOPS, a new opportunity to detect exocomets is available. Combining data from CHEOPS and TESS we investigate the lightcurve of 5 Vul, an A-type star with detected variability in spectroscopy, to search for non periodic transits that could indicate the presence of dusty cometary tails in the system. While we did not find any evidence of minor bodies, the high precision of the data, along with the combination with previous spectroscopic results and models, allows for an estimation of the sizes and spatial distribution of the exocomets.

Authors:Óscar Carrión-González, Raphael Moreno, Emmanuel Lellouch, Thibault Cavalié, Sandrine Guerlet, Gwenaël Milcareck, Aymeric Spiga, Noé Clément, Jérémy Leconte

Abstract: Neptune's tropospheric winds are among the most intense in the Solar System, but the dynamical mechanisms that produce them remain uncertain. Measuring wind speeds at different pressure levels may help understand the atmospheric dynamics of the planet. The goal of this work is to directly measure winds in Neptune's stratosphere with ALMA Doppler spectroscopy. We derived the Doppler lineshift maps of Neptune at the CO(3-2) and HCN(4-3) lines at 345.8 GHz ($\lambda$~0.87 mm) and 354.5 GHz (0.85 mm), respectively. For that, we used spectra obtained with ALMA in 2016 and recorded with a spatial resolution of ~0.37" on Neptune's 2.24" disk. After subtracting the planet solid rotation, we inferred the contribution of zonal winds to the measured Doppler lineshifts at the CO and HCN lines. We developed an MCMC-based retrieval methodology to constrain the latitudinal distribution of wind speeds. We find that CO(3-2) and HCN(4-3) lines probe the stratosphere of Neptune at pressures of $2^{+12}_{-1.8}$ mbar and $0.4^{+0.5}_{-0.3}$ mbar, respectively. The zonal winds at these altitudes are less intense than the tropospheric winds based on cloud tracking from Voyager observations. We find equatorial retrograde (westward) winds of $-180^{+70}_{-60}$ m/s for CO, and $-190^{+90}_{-70}$ m/s for HCN. Wind intensity decreases towards mid-latitudes, and wind speeds at 40$^\circ$S are $-90^{+50}_{-60}$ m/s for CO, and $-40^{+60}_{-80}$ m/s for HCN. Wind speeds become 0 m/s at about 50$^\circ$S, and we find that the circulation reverses to a prograde jet southwards of 60$^\circ$S. Overall, our direct stratospheric wind measurements match previous estimates from stellar occultation profiles and expectations based on thermal wind equilibrium. These are the first direct Doppler wind measurements performed on the Icy Giants, opening a new method to study and monitor their stratospheric dynamics.

Authors:David Kipping

Abstract: Accurate quantification of the signal-to-noise ratio (SNR) of a given observational phenomenon is central to associated calculations of sensitivity, yield, completeness and occurrence rate. Within the field of exoplanets, the SNR of a transit has been widely assumed to be the formula that one would obtain by assuming a boxcar light curve, yielding an SNR of the form $(\delta/\sigma_0) \sqrt{D}$. In this work, a general framework is outlined for calculating the SNR of any analytic function and it is applied to the specific case of a trapezoidal transit as a demonstration. By refining the approximation from boxcar to trapezoid, an improved SNR equation is obtained that takes the form $(\delta/\sigma_0) \sqrt{(T_{14}+2T_{23})/3}$. A solution is also derived for the case of a trapezoid convolved with a top-hat, corresponding to observations with finite integration time, where it is proved that SNR is a monotonically decreasing function of integration time. As a rule of thumb, integration times exceeding $T_{14}/3$ lead to a 10% loss in SNR. This work establishes that the boxcar transit is approximate and it is argued that efforts to calculate accurate completeness maps or occurrence rate statistics should either use the refined expression, or even better numerically solve for the SNR of a more physically complete transit model.

Authors:Ginger Frame, David J. Armstrong, Heather M. Cegla, Jorge Fernández Fernández, Ares Osborn, Vardan Adibekyan, Karen A. Collins, Elisa Delgado Mena, Steven Giacalone, John F. Kielkopf, Nuno C. Santos, Sérgio G. Sousa, Keivan G. Stassun, Carl Ziegler, David R. Anderson, Susana C. C. Barros, Daniel Bayliss, César Briceño, Dennis M. Conti, Courtney D. Dressing, Xavier Dumusque, Pedro~Figueira, William Fong, Samuel Gill, Faith Hawthorn, Jon M. Jenkins, Eric L. N. Jensen, Marcelo Aron F. Keniger, David W. Latham, Nicholas Law, Jack J. Lissauer, Andrew W. Mann, Louise D. Nielsen, Hugh Osborn, Martin Paegert, Sara Seager, Richard P. Schwarz, Avi Shporer, Gregor Srdoc, Paul A. Strøm, Joshua N. Winn, Peter J. Wheatley

Abstract: We present the discovery and confirmation of a transiting hot, bloated Super-Neptune using photometry from TESS and LCOGT and radial velocity measurements from HARPS. The host star TOI-2498 is a V = 11.2, G-type (T$_{eff}$ = 5905 $\pm$ 12K) solar-like star with a mass of 1.12 $\pm$ 0.02 M$_{\odot}$ and a radius of 1.26 $\pm$ 0.04 R$_{\odot}$. The planet, TOI-2498 b, orbits the star with a period of 3.7 days, has a radius of 6.1 $\pm$ 0.3 R$_{\oplus}$, and a mass of 35 $\pm$ 4 M$_{\oplus}$. This results in a density of 0.86 $\pm$ 0.25 g cm$^{-3}$. TOI-2498 b resides on the edge of the Neptune desert; a region of mass-period parameter space in which there appears to be a dearth of planets. Therefore TOI-2498 b is an interesting case to study to further understand the origins and boundaries of the Neptune desert. Through modelling the evaporation history, we determine that over its $\sim$3.6 Gyr lifespan, TOI-2498 b has likely reduced from a Saturn sized planet to its current radius through photoevaporation. Moreover, TOI-2498 b is a potential candidate for future atmospheric studies searching for species like water or sodium in the optical using high-resolution, and for carbon based molecules in the infra-red using JWST.

Authors:Manasvi Lingam, Amedeo Balbi, Swadesh M. Mahajan

Abstract: Current research indicates that (sub)surface ocean worlds essentially devoid of subaerial landmasses (e.g., continents) are common in the Milky Way, and that these worlds could host habitable conditions, thence raising the possibility that life and technological intelligence (TI) may arise in such aquatic settings. It is known, however, that TI on Earth (i.e., humans) arose on land. Motivated by these considerations, we present a Bayesian framework to assess the prospects for the emergence of TIs in land- and ocean-based habitats (LBHs and OBHs). If all factors are equally conducive for TIs to arise in LBHs and OBHs, we demonstrate that the evolution of TIs in LBHs (which includes humans) might have very low odds of roughly $1$-in-$10^3$ to $1$-in-$10^4$, thus outwardly contradicting the Copernican Principle. Hence, we elucidate three avenues whereby the Copernican Principle can be preserved: (i) the emergence rate of TIs is much lower in OBHs, (ii) the habitability interval for TIs is much shorter in OBHs, and (iii) only a small fraction of worlds with OBHs comprise appropriate conditions for effectuating TIs. We also briefly discuss methods for empirically falsifying our predictions, and comment on the feasibility of supporting TIs in aerial environments.

Authors:Giovanni Picogna, Carolina Schäfer, Barbara Ercolano, Christian Rab, Rafael Franz, Matías Gárate

Abstract: Photoevaporative disc winds play a key role in our understanding of circumstellar disc evolution, especially in the final stages, and they might affect the planet formation process and the final location of planets. The study of transition discs (i.e. discs with a central dust cavity) is central for our understanding of the photoevaporation process and disc dispersal. However, we need to distinguish cavities created by photoevaporation from those created by giant planets. Theoretical models are necessary to identify possible observational signatures of the two different processes, and models to find the differences between the two processes are still lacking. In this paper we study a sample of transition discs obtained from radiation-hydrodynamic simulations of internally photoevaporated discs, and focus on the dust dynamics relevant for current ALMA observations. We then compared our results with gaps opened by super Earths/giant planets, finding that the photoevaporated cavity steepness depends mildly on gap size, and it is similar to that of a 1 Jupiter mass planet. However, the dust density drops less rapidly inside the photoevaporated cavity compared to the planetary case due to the less efficient dust filtering. This effect is visible in the resulting spectral index, which shows a larger spectral index at the cavity edge and a shallower increase inside it with respect to the planetary case. The combination of cavity steepness and spectral index might reveal the true nature of transition discs.

Authors:Georgina Dransfield, Mathilde Timmermans, Amaury H. M. J. Triaud, Martín Dévora-Pajares, Christian Aganze, Khalid Barkaoui, Adam J. Burgasser, Karen A. Collins, Marion Cointepas, Elsa Ducrot, Maximilian N. Günther, Steve B. Howell, Catriona A. Murray, Prajwal Niraula, Benjamin V. Rackham, Daniel Sebastian, Keivan G. Stassun, Sebastián Zúñiga-Fernández, José Manuel Almenara, Xavier Bonfils, François Bouchy, Christopher J. Burke, David Charbonneau, Jessie L. Christiansen, Laetitia Delrez, Tianjun Gan, Lionel J. García, Michaël Gillon, Yilen Gómez Maqueo Chew, Katharine M. Hesse, Matthew J. Hooton, Giovanni Isopi, Emmanuël Jehin, Jon M. Jenkins, David W. Latham, Franco Mallia, Felipe Murgas, Peter P. Pedersen, Francisco J. Pozuelos, Didier Queloz, David R. Rodriguez, Nicole Schanche, Sara Seager, Gregor Srdoc, Chris Stockdale, Joseph D. Twicken, Roland Vanderspek, Robert Wells, Joshua N. Winn, Julien de Wit, Aldo Zapparata

Abstract: A new generation of observatories is enabling detailed study of exoplanetary atmospheres and the diversity of alien climates, allowing us to seek evidence for extraterrestrial biological and geological processes. Now is therefore the time to identify the most unique planets to be characterised with these instruments. In this context, we report on the discovery and validation of TOI-715 b, a $R_{\rm b}=1.55\pm 0.06\rm R_{\oplus}$ planet orbiting its nearby ($42$ pc) M4 host (TOI-715/TIC 271971130) with a period $P_{\rm b} = 19.288004_{-0.000024}^{+0.000027}$ days. TOI-715 b was first identified by TESS and validated using ground-based photometry, high-resolution imaging and statistical validation. The planet's orbital period combined with the stellar effective temperature $T_{\rm eff}=3075\pm75~\rm K$ give this planet an instellation $S_{\rm b} = 0.67_{-0.20}^{+0.15}~\rm S_\oplus$, placing it within the most conservative definitions of the habitable zone for rocky planets. TOI-715 b's radius falls exactly between two measured locations of the M-dwarf radius valley; characterising its mass and composition will help understand the true nature of the radius valley for low-mass stars. We demonstrate TOI-715 b is amenable for characterisation using precise radial velocities and transmission spectroscopy. Additionally, we reveal a second candidate planet in the system, TIC 271971130.02, with a potential orbital period of $P_{02} = 25.60712_{-0.00036}^{+0.00031}$ days and a radius of $R_{02} = 1.066\pm0.092\,\rm R_{\oplus}$, just inside the outer boundary of the habitable zone, and near a 4:3 orbital period commensurability. Should this second planet be confirmed, it would represent the smallest habitable zone planet discovered by TESS to date.

Authors:Eliza M. -R. Kempton, Michael Zhang, Jacob L. Bean, Maria E. Steinrueck, Anjali A. A. Piette, Vivien Parmentier, Isaac Malsky, Michael T. Roman, Emily Rauscher, Peter Gao, Taylor J. Bell, Qiao Xue, Jake Taylor, Arjun B. Savel, Kenneth E. Arnold, Matthew C. Nixon, Kevin B. Stevenson, Megan Mansfield, Sarah Kendrew, Sebastian Zieba, Elsa Ducrot, Achrène Dyrek, Pierre-Olivier Lagage, Keivan G. Stassun, Gregory W. Henry, Travis Barman, Roxana Lupu, Matej Malik, Tiffany Kataria, Jegug Ih, Guangwei Fu, Luis Welbanks, Peter McGill

Abstract: There are no planets intermediate in size between Earth and Neptune in our Solar System, yet these objects are found around a substantial fraction of other stars. Population statistics show that close-in planets in this size range bifurcate into two classes based on their radii. It is hypothesized that the group with larger radii (referred to as "sub-Neptunes") is distinguished by having hydrogen-dominated atmospheres that are a few percent of the total mass of the planets. GJ 1214b is an archetype sub-Neptune that has been observed extensively using transmission spectroscopy to test this hypothesis. However, the measured spectra are featureless, and thus inconclusive, due to the presence of high-altitude aerosols in the planet's atmosphere. Here we report a spectroscopic thermal phase curve of GJ 1214b obtained with JWST in the mid-infrared. The dayside and nightside spectra (average brightness temperatures of 553 $\pm$ 9 and 437 $\pm$ 19 K, respectively) each show >3$\sigma$ evidence of absorption features, with H$_2$O as the most likely cause in both. The measured global thermal emission implies that GJ 1214b's Bond albedo is 0.51 $\pm$ 0.06. Comparison between the spectroscopic phase curve data and three-dimensional models of GJ 1214b reveal a planet with a high metallicity atmosphere blanketed by a thick and highly reflective layer of clouds or haze.

Authors:Adam T. Stevenson The Open University, Milton Keynes, UK, Carole A. Haswell The Open University, Milton Keynes, UK, John R. Barnes The Open University, Milton Keynes, UK, Joanna K. Barstow The Open University, Milton Keynes, UK, Zachary O. B. Ross The Open University, Milton Keynes, UK

Abstract: We present additional HARPS radial velocity observations of the highly eccentric ($e \sim 0.6$) binary system DMPP-3AB, which comprises a K0V primary and a low-mass companion at the hydrogen burning limit. The binary has a $507$ d orbital period and a $1.2$ au semi-major axis. The primary component harbours a known $2.2$ M$_{\oplus}$ planet, DMPP-3A b, with a $6.67$ day orbit. New HARPS measurements constrain periastron passage for the binary orbit and add further integrity to previously derived solutions for both companion and planet orbits. Gaia astrometry independently confirms the binary orbit, and establishes the inclination of the binary is $63.89 \pm 0.78 ^{\circ}$. We performed dynamical simulations which establish that the previously identified $\sim800$ d RV signal cannot be attributed to an orbiting body. The additional observations, a deviation from strict periodicity, and our new analyses of activity indicators suggest the $\sim800$ d signal is caused by stellar activity. We conclude that there may be long period planet 'detections' in other systems which are similar misinterpreted stellar activity artefacts. Without the unusual eccentric binary companion to the planet-hosting star we could have accepted the $\sim800$ d signal as a probable planet. Further monitoring of DMPP-3 will reveal which signatures can be used to most efficiently identify these imposters. We also report a threshold detection (0.2 per cent FAP) of a $\sim2.26$ d periodicity in the RVs, potentially attributed to an Earth-mass S-type planet interior to DMPP-3A b.

Authors:Orhan Erece, Irek Khamitov, Murat Kaplan, Yucel Kilic, Hee-Jae Lee, Myung-Jin Kim, Ilfan F. Bikmaevc, Rustem I. Gumerov, Eldar N. Irtuganov

Abstract: In this study, we carried out photometric, spectroscopic, and for the first time, polarimetric observations of the Amor-type near-Earth asteroid (2059) Baboquivari. Our findings represent the first reliable determination of Baboquivari's physical properties. We used data from a 1m-class telescope (T100) along with ALCDEF data for photometric analyses and a 1.5-m-class telescope (RTT150) for polarimetric, spectroscopic, and additional photometric observations. We obtained the synodic rotation period of Baboquivari as 129.93 +/- 2.31 hours and the standard phase function parameters H and G as 16.05 +/- 0.05, 0.22 +/- 0.02, respectively. Our colour index (V-R) measurement of 0.45 +/- 0.02 is consistent with spectroscopic observations, indicating an S (or sub-S) spectral type. Using the polarimetric and spectroscopic data, we found that the geometric albedo is 0.15 +/- 0.03, and the spectral type is Sq. Based on the estimated albedo and absolute magnitude, Baboquivari has an effective diameter of 2.12 +/- 0.21 km. Due to the scattered data in the light curve, its slow rotation and location among the NEAs suggest that Baboquivari may be a non-principal axis (NPA) rotator.

Authors:Shifeng Jin, Munan Hao, Zhongnan Guo, Bohao Yin, Yuxin Ma, Lijun Deng, Xu Chen, Yanpeng Song, Cheng Cao, Congcong Chai, Yunqi Ma, Jiangang Guo, Xiaolong Chen

Abstract: The origin and distribution of lunar water are among the most important issues in understanding the earth-moon system. After more than half a century of laboratory research and remote detection, only hydroxyl contained minerals and lunar ice (H2O) are identified. Here we report the discovery of a hydrous mineral (NH4)MgCl3(H2O)6 in the lunar soil returned by Chang'e-5 mission, which contains 417,000 parts per million H2O. The determined structure and composition are similar to novograblenovite-a terrestrial fumarole mineral formed by reaction of hot basalt in water-rich volcanic gases, whereas the measured isotope composition delta37Cl reached 20.4 parts per thousand, a high value that only found in lunar minerals. We rule out the possibility that this hydrate originated from terrestrial contaminants or rocket exhaust through analysis of its chemical, isotopic compositions as well as the formation conditions. Our finding indicates that water can exist on some parts of the sunlit Moon in the form of hydrate compounds. Moreover, this hydrate is rich in ammonium, providing new information in understanding the origin of the Moon.

Authors:Amedeo Balbi, Manasvi Lingam

Abstract: The probability that life spontaneously emerges in a suitable environment (abiogenesis) is one of the major unknowns in astrobiology. Assessing its value is impeded by the lack of an accepted theory for the origin of life, and is further complicated by the existence of selection biases. Appealing uncritically to some version of the ``Principle of Mediocrity'' -- namely, the supposed typicality of what transpired on Earth -- is problematic on empirical or logical grounds. In this paper, we adopt a Bayesian statistical approach to put on rigorous footing the inference of lower bounds for the probability of abiogenesis, based on current and future evidence. We demonstrate that the single datum that life has appeared at least once on Earth merely sets weak constraints on the minimal probability of abiogenesis. In fact, the {\it a priori} probability assigned to this event (viz., optimistic, pessimistic or agnostic prior) exerts the strongest influence on the final result. We also show that the existence of a large number of habitable worlds does not necessarily imply, by itself, a high probability that life should be common in the universe. Instead, as delineated before, the choice of prior, which is subject to uncertainty (i.e., admits multiple scenarios), strongly influences the likelihood of life being common. If habitable worlds are uncommon, for an agnostic prior, a deterministic scenario for the origin of life might be favoured over one where abiogenesis is a fluke event.

Authors:Fabian Binkert, Judit Szulágyi, Til Birnstiel

Abstract: The motion of solid particles embedded in gaseous protoplanetary disks is influenced by turbulent fluctuations. Consequently, the dynamics of moderately to weakly coupled solids can be distinctly different from the dynamics of the gas. Additionally, gravitational perturbations from an embedded planet can further impact the dynamics of solids. In this work, we investigate the combined effects of turbulent fluctuations and planetary dust stirring in a protoplanetary disk on three-dimensional dust morphology and on synthetic ALMA continuum observations. We carry out 3D radiative two-fluid (gas+1-mm-dust) hydrodynamic simulations in which we explicitly model the gravitational perturbation of a Jupiter-mass planet. We derived a new momentum-conserving turbulent diffusion model that introduces a turbulent pressure to the pressureless dust fluid to capture the turbulent transport of dust. The model implicitly captures the effects of orbital oscillations and reproduces the theoretically predicted vertical settling-diffusion equilibrium. We find a Jupiter-mass planet to produce distinct and large-scale three-dimensional flow structures in the mm-size dust, which vary strongly in space. We quantify these effects by locally measuring an effective vertical diffusivity (equivalent alpha) and find azimuthally averaged values in a range $\delta_\mathrm{eff}\sim5\cdot 10^{-3} - 2\cdot 10^{-2}$ and local peaks at values of up to $\delta_\mathrm{eff}\sim3\cdot 10^{-1}$. In synthetic ALMA continuum observations of inclined disks, we find effects of turbulent diffusion to be observable, especially at disk edges, and effects of planetary dust stirring in edge-on observations.

Authors:M. A. Cordiner, N. X. Roth, S. N. Milam, G. Villanueva, D. Bockelee-Morvan, A. J. Remijan, S. B. Charnley, N. Biver, D. C. Lis, C. Qi, B. Bonev, J. Crovisier, J. Boissier

Abstract: Gas-phase molecules in cometary atmospheres (comae) originate primarily from (1) outgassing by the nucleus, (2) sublimation of icy grains in the near-nucleus coma, and (3) coma (photo-)chemical processes. However, the majority of cometary gases observed at radio wavelengths have yet to be mapped, so their production/release mechanisms remain uncertain. Here we present observations of six molecular species towards comet 46P/Wirtanen, obtained using the Atacama Large Millimeter/submillimeter Array (ALMA) during the comet's unusually close (~0.1 au) approach to Earth in December 2018. Interferometric maps of HCN, CH$_3$OH, CH$_3$CN, H$_2$CO, CS and HNC were obtained at an unprecedented sky-projected spatial resolution of up to 25 km, enabling the nucleus and coma sources of these molecules to be accurately quantified. The HCN, CH$_3$OH and CH$_3$CN spatial distributions are consistent with the production from direct outgassing from (or very near to) the nucleus, with a significant proportion (~50%) of the observed CH$_3$OH originating from sublimation of icy grains in the near-nucleus coma. On the other hand, H$_2$CO, CS and HNC originate primarily from distributed coma sources. The HCN, CH$_3$OH and HNC abundances in 46P are consistent with the average values previously observed in comets, whereas the H$_2$CO, CH$_3$CN and CS abundances are relatively low.

Authors:Joseph R. Masiero, Maxime Devogele, Isabella Macias, Joahan Castaneda Jaimes, Alberto Cellino

Abstract: Polarization phase-curve measurements provide a unique constraint on the surface properties of asteroids that are complementary to those from photometry and spectroscopy, and have led to the identification of the ``Barbarian'' asteroids as a class of objects with highly unusual surfaces. We present new near-infrared polarimetric observations of six Barbarian asteroids obtained with the WIRC+Pol instrument on the Palomar Hale telescope. We find a dramatic change in polarimetric behavior from visible to near-infrared for these objects, including a change in the polarimetric inversion angle that is tied to the index of refraction of the surface material. Our observations support a two-phase surface composition consisting of high albedo, high index of refraction inclusions with a small optical size scale embedded in a dark matrix material more closely related to C-complex asteroids. These results are consistent with the interpretation that the Barbarians are remnants of a population of primitive bodies that formed shortly after CAIs. Near-infrared polarimetry provides a direct test of the constituent grains of asteroid surfaces.

Authors:Oscar Fuentes-Muñoz, Daniel J. Scheeres, Davide Farnocchia, Ryan S. Park

Abstract: The catalog of km-sized near-Earth objects (NEOs) is nearly complete. Typical impact monitoring analyses search for possible impacts over the next 100 years and none of the km-sized objects represent an impact threat over that time interval. Assessing the impact risk over longer time scales is a challenge since orbital uncertainties grow. To overcome this limitation we analyze the evolution of the Minimum Orbit Intersection Distance (MOID), which bounds the closest possible encounters between the asteroid and the Earth. The evolution of the MOID highlights NEOs that are in the vicinity of the Earth for longer periods of time, and we propose a method to estimate the probability of a deep Earth encounter during these periods. This metric is used to rank the km-sized catalog in terms of their long-term impact hazard to identify targets of potential interest for additional observation and exploration.

Authors:Paul B. Rimmer

Abstract: I show that exoplanets can be used to test origins scenarios. Origins scenarios start with certain initial conditions, proceed via a network of chemical reactions and, if successful, result in a chemistry that is closer to a living system than the initial conditions. Exoplanet environments can be applied to test each of these three aspects of origins scenarios. I show what tests can be applied to the UV-driven cyanosulfidic scenario and how the application of some of these tests has already falsified certain versions of this scenario. Testing initial conditions has replaced certain reactants with others and has affected the overall chemical network underlying the cyanosulfidic scenario. The sequence of reactions the scenario invokes provide a predicted upper limit on the ubiquity of life in the universe that has ample room for improvement. The outcome of the experiments in different environments is part of a predicted distribution of biosignature detections that can be compared to future observed distributions.

Authors:A. Castro-González, O. D. S. Demangeon, J. Lillo-Box, C. Lovis, B. Lavie, V. Adibekyan, L. Acuña, M. Deleuil, A. Aguichine, M. R. Zapatero Osorio, H. M. Tabernero, J. Davoult, Y. Alibert, N. Santos, S. G. Sousa, A. Antoniadis-Karnavas, F. Borsa, J. N. Winn, C. Allende Prieto, P. Figueira, J. M. Jenkins, A. Sozzetti, M. Damasso, A. M. Silva, N. Astudillo-Defru, S. C. C. Barros, X. Bonfils, S. Cristiani, P. Di Marcantonio, J. I. González Hernández, G. Lo Curto, C. J. A. P. Martins, N. J. Nunes, E. Palle, F. Pepe, S. Seager, A. Suárez Mascareño

Abstract: Small planets located at the lower mode of the bimodal radius distribution are generally assumed to be composed of iron and silicates in a proportion similar to that of the Earth. However, recent discoveries are revealing a new group of low-density planets that are inconsistent with that description. We intend to confirm and characterize the TESS planet candidate TOI-244.01, which orbits the bright ($K$ = 7.97 mag), nearby ($d$ = 22 pc), and early-type (M2.5 V) M-dwarf star GJ 1018 with an orbital period of 7.4 days. We used Markov Chain Monte Carlo methods to model 57 precise radial velocity measurements acquired by the ESPRESSO spectrograph together with TESS photometry and complementary HARPS data. We find TOI-244 b to be a super-Earth with a radius of $R_{\rm p}$ = 1.52 $\pm$ 0.12 $\rm R_{\oplus}$ and a mass of $M_{\rm p}$ = 2.68 $\pm$ 0.30 $\rm M_{\oplus}$. These values correspond to a density of $\rho$ = 4.2 $\pm$ 1.1 $\rm g \cdot cm^{-3}$, which is below what would be expected for an Earth-like composition. We find that atmospheric loss processes may have been efficient to remove a potential primordial hydrogen envelope, but high mean molecular weight volatiles such as water could have been retained. Our internal structure modeling suggests that TOI-244 b has a $479^{+128}_{-96}$ km thick hydrosphere over a 1.17 $\pm$ 0.09 $\rm R_{\oplus}$ solid structure composed of a Fe-rich core and a silicate-dominated mantle compatible with that of the Earth. On a population level, we find two tentative trends in the density-metallicity and density-insolation parameter space for the low-density super-Earths, which may hint at their composition. With a 8$\%$ precision in radius and 12$\%$ precision in mass, TOI-244 b is among the most precisely characterized super-Earths, which, together with the likely presence of an extended hydrosphere, makes it a key target for atmospheric observations.

Authors:Sergei Nayakshin, James E. Owen, Vardan Elbakyan

Abstract: Disc accretion rate onto low mass protostar FU Ori suddenly increased hundreds of times 85 years ago and remains elevated to this day. We show that the sum of historic and recent observations challenges existing FU Ori models. We build a theory of a new process, Extreme Evaporation (EE) of young gas giant planets in discs with midplane temperatures exceeding 30, 000 K. Such temperatures are reached in the inner 0.1 AU during thermal instability bursts. In our 1D time-dependent code the disc and an embedded planet interact through gravity, heat, and mass exchange. We use disc viscosity constrained by simulations and observations of dwarf novae instabilities, and we constrain planet properties with a stellar evolution code. We show that dusty gas giants born in the outer self-gravitating disc reach the innermost disc in a $\sim$ 10,000 years with radius of $\sim 10 R_J$. We show that their EE rates are $\sim 10^{-5}$ Msun/yr; if this exceeds the background disc accretion activity then the system enters a planet-sourced mode. Like a stellar secondary in mass-transferring binaries, the planet becomes the dominant source of matter for the star, albeit for $\sim$ O(100) years. We find that a $\sim$ 6 Jupiter mass planet evaporating in a disc fed at a time-averaged rate of $\sim 10^{-6}$ Msun/yr appears to explain all that we currently know about FU Ori accretion outburst. More massive planets and/or planets in older less massive discs do not experience EE process. Future FUOR modelling may constrain planet internal structure and evolution of the earliest discs.

Authors:E. Kleisioti, D. Dirkx, M. Rovira-Navarro, M. A. Kenworthy

Abstract: Exomoons are expected to orbit gas giant exoplanets just as moons orbit solar system planets. Tidal heating is present in solar system satellites and it can heat up their interior depending on their orbital and interior properties. We aim to identify a Tidally Heated Exomoon's (THEM) orbital parameter space that would make it observable in infrared wavelengths with MIRI/JWST around $\epsilon$ Eridani b. We study the possible constraints on orbital eccentricity and interior properties that a successful THEM detection in infrared wavelengths can bring. We also investigate what exomoon properties need to be independently known in order to place these constraints. We use a coupled thermal-tidal model to find stable equilibrium points between the tidally produced heat and heat transported within a moon. For the latter, we consider a spherical and radially symmetric satellite with heat being transported via magma advection in a sub-layer of melt (asthenosphere) and convection in the lower mantle. We incorporate uncertainties in the interior and tidal model parameters to assess the fraction of simulated moons that would be observable with MIRI. We find that a $2 R_{Io}$ THEM orbiting $\epsilon$ Eridani b with an eccentricity of 0.02, would need to have a semi-major axis of 4 planetary Roche-radii for 100% of the simulations to produce an observable moon. These values are comparable with the orbital properties of gas giant solar system satellites. We place similar constraints for eccentricities up to 0.1. We conclude that if the semi-major axis and radius of the moon are known (eg. with exomoon transits), tidal dissipation can constrain the orbital eccentricity and interior properties of the satellite, such as the presence of melt and the thickness of the melt containing sub-layer.

Authors:Cecile Engrand, Jérémie Lasue, Diane H. Wooden, Mike E. Zolensky

Abstract: Cometary dust particles are best preserved remnants of the matter present at the onset of the formation of the Solar System. Space missions, telescopic observations and laboratory analyses advanced the knowledge on the properties of cometary dust. Cometary samples were returned from comet 81P/Wild2 by the Stardust mission. The chondritic (porous) anhydrous interplanetary dust particles and chondritic porous micrometeorites, and the ultracarbonaceous Antarctic micrometeorites (UCAMMs) also show strong evidence for a cometary origin. The composition of cometary dust is generally chondritic, but with high C and N compared with CI. The cometary organic matter is mixed with minor amounts of crystalline and amorphous minerals. The most abundant crystalline minerals are ferromagnesian silicates, refractory minerals and low Ni Fe sulfides are also present. The presence of carbonates in cometary dust is still debated, but a phyllosilicate-like phase was observed in a UCAMM. GEMS phases are usually abundant. Some of the organic matter present in cometary dust particle resembles the insoluble organic matter present in primitive meteorites, but amorphous carbon and exotic (e.g. N-rich) organic phases are also present. The H isotopic composition of the organic matter traces a formation at very low temperatures, in the protosolar cloud or in the outer regions of the protoplanetary disk. The presolar dust concentration in cometary dust can reach about 1%, which is the most elevated value observed in extraterrestrial samples. The differential size distribution of cometary dust in comet trails is well represented by a power-law distribution with a mean power index N typically ranging from -3 to -4. Polarimetric and light scattering studies suggest mixtures of porous agglomerates of sub-micrometer minerals with organic matter. Cometary dust particles have low tensile strength, and low density.

Authors:F. Lienhard, A. Mortier, H. M. Cegla, A. Collier Cameron, B. Klein, C. A. Watson

Abstract: The photospheric unsigned magnetic flux has been shown to be highly correlated with radial velocity (RV) variations caused by solar surface activity. This activity indicator is therefore a prime candidate to unlock the potential of RV surveys to discover Earth twins orbiting Sun-like stars. We show for the first time how a precise proxy of the unsigned magnetic flux ($\Delta\alpha B^2$) can be obtained from Sun-as-a-star intensity spectra by harnessing the magnetic information contained in over 4000 absorption lines in the wavelength range from 380 to 690 nm. This novel activity proxy can thus be obtained from the same spectra from which RVs are routinely extracted. We derived $\Delta\alpha B^2$ from 500 randomly selected spectra from the HARPS-N public solar data set, which spans from 2015 to 2018. We compared our estimates with the unsigned magnetic flux values from the Solar Dynamics Observatory (SDO) finding excellent agreement (median absolute deviation: 4.9 per cent). The extracted indicator $\Delta\alpha B^2$ correlates with SDO's unsigned magnetic flux estimates on the solar rotational timescale (Pearson correlation coefficient 0.67) and on the three-year timescale of our data set (correlation coefficient 0.91). We find correlations of $\Delta\alpha B^2$ with the HARPS-N solar RV variations of 0.49 on the rotational timescale and 0.78 on the three-year timescale. The Pearson correlation of $\Delta\alpha B^2$ with the RVs is found to be greater than the correlation of the classical activity indicators with the RVs. For solar-type stars, $\Delta\alpha B^2$ therefore represents the best simultaneous activity proxy known to date.

Authors:Laurent Schönau, Jens Teiser, Tunahan Demirci, Kolja Joeris, Tetyana Bila, F. Chioma Onyeagusi, Miriam Fritscher, Gerhard Wurm

Abstract: Planetesimals are born fragile and are subject to destruction by wind erosion as they move through the gas of a protoplanetary disk. In microgravity experiments, we determined the shear stress necessary for erosion of a surface consisting of 1 mm dust pebbles down to 1 Pa ambient pressure. This is directly applicable to protoplanetary disks. Even pebble pile planetesimals with low eccentricities of 0.1 cannot survive inside of 1 au in a minimum-mass solar nebula, and safe zones for planetesimals with higher eccentricities are located even farther out.

Authors:Cristiano Longarini, Philip J. Armitage, Giuseppe Lodato, Daniel J. Price, Simone Ceppi

Abstract: Young protostellar discs are likely to be both self-gravitating, and to support grain growth to sizes where the particles decoupled from the gas. This combination could lead to short-wavelength fragmentation of the solid component in otherwise non-fragmenting gas discs, forming Earth-mass solid cores during the Class 0/I stages of Young Stellar Object evolution. We use three-dimensional smoothed particle hydrodynamics simulations of two-fluid discs, in the regime where the Stokes number of the particles St>1, to study how the formation of solid clumps depends on the disc-to-star mass ratio, the strength of gravitational instability, and the Stokes number. Gravitational instability of the simulated discs is sustained by local cooling. We find that the ability of the spiral structures to concentrate solids increases with the cooling time, and decreases with the Stokes number, while the relative dynamical temperature between gas and dust of the particles decreases with the cooling time and the disc-to-star mass ratio, and increases with the Stokes number. Dust collapse occurs in a subset of high disc mass simulations, yielding clumps whose mass is close to linear theory estimates, namely 1-10 Earth masses. Our results suggest that if planet formation occurs via this mechanism, the best conditions correspond to near the end of the self-gravitating phase, when the cooling time is long and the Stokes number close to unity.

Authors:Thomas Tarrants, Andrew Li

Abstract: The nearby M2 dwarf GJ 3470 has been the target of considerable interest after the discovery of a transiting short-period Neptune-sized planet. Recently, claims regarding the existence of additional transiting planets has gotten some attention, suggesting both the presence of a gas giant in the habitable zone, and that the system hosts a remarkable co-orbital gas giant configuration. We show that the existence of these three additional planets are readily amenable to testing with available data from both ground-based radial velocity data and space-based TESS photometry. A periodogram search of the available radial velocities show no compelling signals at the claimed periods, and the TESS photometry effectively rules out these planets assuming a transiting configuration. While it is doubtlessly possible that additional planets orbit GJ 3470, there is no evidence to date for their existence, and the available data conclusively rule out any planets similar to those considered in this text.

Authors:Eli Galanti, Yohai Kaspi, Tristan Guillot

Abstract: The shape of the two gas giants, Jupiter and Saturn, is determined primarily by their rotation rate, and interior density distribution. It is also affected by their zonal winds, causing an anomaly of O(10 km) at low latitudes. However, uncertainties in the observed cloud-level wind and the polar radius, translate to an uncertainty in the shape with the same order of magnitude. The Juno (Jupiter) and Cassini (Saturn) missions gave unprecedented accurate gravity measurements, constraining better the uncertainty in the wind structure. Using an accurate shape calculation, and a joint optimization, given both gravity and radio-occultation measurements, we calculate the possible range of dynamical height for both planets. We find that for Saturn there is an excellent match to the radio-occultation measurements, while at Jupiter such a match is not achieved. This may point to deviations from a barotropic flow above the cloud level, which might be tested with the forthcoming radio-occultation measurements by Juno.

Authors:Christopher D. P. Duffy, Gregoire Canchon, Thomas J. Haworth, Edward Gillen, Samir Chitnavis, Conrad W. Mullineaux

Abstract: Here we discuss the feasibility of photosynthesis on Earth-like rocky planets in close orbit around ultra-cool red dwarf stars. Stars of this type have very limited emission in the \textit{photosynthetically active} region of the spectrum ($400 - 700$ nm), suggesting that they may not be able to support oxygenic photosynthesis. However, photoautotrophs on Earth frequently exploit very dim environments with the aid of highly structured and extremely efficient antenna systems. Moreover, the anoxygenic photosynthetic bacteria, which do not need to oxidize water to source electrons, can exploit far red and near infrared light. Here we apply a simple model of a photosynthetic antenna to a range of model stellar spectra, ranging from ultra-cool (2300 K) to Sun-like (5800 K). We assume that a photosynthetic organism will evolve an antenna that maximizes the rate of energy input while also minimizing fluctuations. The latter is the 'noise cancelling' principle recently reported by Arp et al. 2020. Applied to the Solar spectrum this predicts optimal antenna configurations in agreement with the chlorophyll Soret absorption bands. Applied to cooler stars, the optimal antenna peaks become redder with decreasing stellar temperature, crossing to the typical wavelength ranges associated with anoxygenic photoautotrophs at $\sim 3300$ K. Lastly, we compare the relative input power delivered by antennae of equivalent size around different stars and find that the predicted variation is within the same order of magnitude. We conclude that low-mass stars do not automatically present light-limiting conditions for photosynthesis but they may select for anoxygenic organisms.

Authors:M. Ould-Elhkim, C. Moutou, J-F. Donati, É. Artigau, P. Fouqué, N. J. Cook, A. Carmona, P. I. Cristofari, E. Martioli, F. Debras, X. Dumusque, J. H. C. Martins, G. Hébrard, C. Cadieux, X. Delfosse, R. Doyon, B. Klein, J. Gomes da Silva, T. Forveille, T. Hood, P. Charpentier

Abstract: Context: Recent advances in the development of precise radial velocity (RV) instruments in the near-infrared (nIR) domain, such as SPIRou, have facilitated the study of M-type stars to more effectively characterize planetary systems. However, the nIR presents unique challenges in exoplanet detection due to various sources of planet-independent signals which can result in systematic errors in the RV data. Aims: In order to address the challenges posed by the detection of exoplanetary systems around M-type stars using nIR observations, we introduce a new data-driven approach for correcting systematic errors in RV data. The effectiveness of this method is demonstrated through its application to the star GJ\,251. Methods: Our proposed method, referred to as \texttt{Wapiti} (Weighted principAl comPonent analysIs reconsTructIon), uses a dataset of per-line RV time-series generated by the line-by-line (LBL) algorithm and employs a weighted principal component analysis (wPCA) to reconstruct the original RV time-series. A multi-step process is employed to determine the appropriate number of components, with the ultimate goal of subtracting the wPCA reconstruction of the per-line RV time-series from the original data in order to correct systematic errors. Results: The application of \texttt{Wapiti} to GJ\,251 successfully eliminates spurious signals from the RV time-series and enables the first detection in the nIR of GJ\,251b, a known temperate super-Earth with an orbital period of 14.2 days. This demonstrates that, even when systematics in SPIRou data are unidentified, it is still possible to effectively address them and fully realize the instrument's capability for exoplanet detection. Additionally, in contrast to the use of optical RVs, this detection did not require to filter out stellar activity, highlighting a key advantage of nIR RV measurements.

Authors:Octavio M. Guilera, Pablo Benitez-Llambay, Marcelo M. Miller Bertolami, Martin E. Pessah

Abstract: Disk solids are critical in many planet formation processes, however, their effect on planet migration remains largely unexplored. Here we assess for the first time this important issue by building on the systematic measurements of dust torques on an embedded planet by Benitez-Llambay & Pessah (2018). Adopting standard models for the gaseous disk and its solid content, we quantify the impact of the dust torque for a wide range of conditions describing the disk/planet system. We show that the total torque can be positive and revert inward planet migration for planetary cores with $M_{\rm p} \lesssim 10 M_\oplus$. We compute formation tracks for low-mass embryos for conditions usually invoked when modeling planet formation processes. Our most important conclusion is that dust torques can have a significant impact on the migration and formation history of planetary embryos. The most important implications of our findings are: $\it{i})$ For nominal dust-to-gas mass ratios $\epsilon \simeq 0.01$, low-mass planets migrate outwards beyond the water ice-line if most of the mass in solids is in particles with Stokes numbers St $\simeq 0.1$. $\it{ii})$. For $\epsilon \gtrsim 0.02-0.05$, solids with small Stokes numbers, St $\simeq 0.01$, can play a dominant role if most of the mass is in those particles. $\it{iii})$ Dust torques have the potential to enable low-mass planetary cores formed in the inner disk to migrate outwards and act as the seed for massive planets at distances of tens of au.

Authors:Christelle Saliby, Agnes Fienga, Arthur Briaud, Anthony Memin, Carianna Herrera

Abstract: The tidal deformations of a planet are often considered as markers of its inner structure. In this work, we use the tide excitations induced by the Sun on Venus for deciphering the nature of its internal layers. In using a Monte Carlo Random Exploration of the space of parameters describing the thickness, density and viscosity of 4 or 5 layer profiles, we were able to select models that can reproduce the observed mass, total moment of inertia, $k_2$ Love number and expected quality factor $Q$. Each model is assumed to have homogeneous layers with constant density, viscosity and rigidity. These models show significant contrasts in the viscosity between the upper mantle and the lower mantle. They also rather favor a S-free core and a slightly hotter lower mantle consistent with previous expectations.

Authors:Lorena Acuna, Magali Deleuil, Olivier Mousis

Abstract: Super-Earths present compositions dominated by refractory materials. However, there is a degeneracy in their interior structure between a planet with no atmosphere and a small Fe content, and a planet with a thin atmosphere and a higher core mass fraction. To break this degeneracy, atmospheric characterization observations are required. We present a self-consistent interior-atmosphere model to constrain the volatile mass fraction, surface pressure, and temperature of rocky planets with water and CO2 atmospheres. These parameters obtained in our analysis can then be used to predict observations in emission spectroscopy and photometry with JWST, which can determine the presence of an atmosphere, and if present, its composition. To obtain the bolometric emission and Bond albedo for an atmosphere in radiative-convective equilibrium, we present the k-uncorrelated approximation for fast computations within our retrieval on planetary mass, radius and host stellar abundances. For the generation of emission spectra, we use our k-correlated atmospheric model. An adaptive MCMC is used for an efficient sampling of the parameter space at low volatile mass fractions. We show how to use our modelling approach to predict observations with JWST for TRAPPIST-1 c and 55 Cancri e. TRAPPIST-1 c's most likely scenario is a bare surface, although the presence of an atmosphere cannot be ruled out. If the emission in the MIRI F1500 filter is 731 ppm or higher, there would be a water-rich atmosphere. For fluxes between 730 and 400 ppm, no atmosphere is present, while low emission fluxes (300 ppm) indicate a CO2-dominated atmosphere. In the case of 55 Cancri e, a combined spectrum with NIRCam and MIRI LRS may present high uncertainties at wavelengths between 3 and 3.7 $\mu$m. However, this does not affect the identification of H2O and CO2 because they do not present spectral features in this wavelength range.

Authors:Yuna G. Kwon, Cyrielle Opitom, Manuela Lippi

Abstract: We report a new imaging spectroscopic observation of Oort-cloud comet C/2017 K2 (hereafter K2) on its way to perihelion at 2.53 au, around a heliocentric distance where H2O ice begins to play a key role in comet activation. Normalized reflectances over 6 500--8 500 AA for its inner and outer comae are 9.7+/-0.5 and 7.2+/-0.3 % (10^3 AA)^-1, respectively, the latter being consistent with the slope observed when the comet was beyond the orbit of Saturn. The dust coma at the time of observation appears to contain three distinct populations: mm-sized chunks prevailing at <~10^3 km; a 10^5-km steady-state dust envelope; and fresh anti-sunward jet particles. the dust chunks dominate the continuum signal and are distributed over a similar radial distance scale as the coma region with redder dust than nearby. they also appear to be co-spatial with OI1D, suggesting that the chunks may accommodate H2O ice with a fraction (>~1 %) of refractory materials. The jet particles do not colocate with any gas species detected. The outer coma spectrum contains three significant emissions from C2(0,0) Swan band, OI1D, and CN(1,0 red band, with an overall deficiency in NH2. Assuming that all OI1D flux results from H2O dissociation, we compute an upper limit on the water production rate Q_H2O of ~7 x 10^28 molec s^-1 (with an uncertainty of a factor of two). the production ratio log[Q_C2/Q_CN] of K2 suggests that the comet has typical carbon-chain composition, with the value potentially changing with distance from the Sun. Our observations suggest that water ice-containing dust chunks (>0.1 mm) near K2's nucleus emitted beyond 4 au may be responsible for its very low gas rotational temperature and the discrepancy between its optical and infrared lights reported at similar heliocentric distances.

Authors:Robert E. Grimm

Abstract: Constraints on the interior structure of the Moon have been derived from its inductive response, principally as measured by the magnetic transfer function (TF) between the distantly orbiting Explorer 35 satellite and the Apollo 12 surface station. The most successful prior studies used a dataset 0.01-1 mHz, so the lunar response could be modeled as a simple dipole. However, earlier efforts also produced transfer functions up to 40 mHz. The smaller electromagnetic skin depth at higher frequency would better resolve the uppermost mantle - where key information about primitive lunar evolution may still be preserved - but requires a multipole treatment. I compute new profiles of electrical conductivity vs depth using both the low-frequency and the full-bandwidth ranges of published Apollo-Explorer TFs. I derive temperature profiles at depths >400 km (<1 mHz) consistent with conductive heat loss and expectations of the iron (and possibly water) content of the mantle. The near-constant iron fraction (Mg# 81 +/- 7) implies either efficient mixing, due to now-defunct convection or perhaps incomplete overturn of gravitationally unstable cumulates following crystallization of the magma ocean. In contrast, the full-bandwidth analysis produced a different conductivity profile that could not be realistically matched by conduction, convection, partial melting, or simple considerations of lateral heterogeneity. I conclude that the TF method at the Moon is unreliable >>1 mHz. Future EM sounding using the magnetotelluric method can operate up to 100s Hz and is largely insensitive to multipole effects, resolving structure to 100 km or less.

Authors:Yinhao Wu, Clément Baruteau, Sergei Nayakshin

Abstract: ALMA has spatially resolved over 200 annular structures in protoplanetary discs, many of which are suggestive of the presence of planets. Constraining the mass of these putative planets is quite degenerate for it depends on the disc physical properties, and for simplicity a steady-state is often assumed whereby the planet position is kept fixed and there is a constant source of dust at the outer edge of the disc. Here we argue against this approach by demonstrating how the planet and dust dynamics can lift degeneracies of such steady-state models. We take main disc parameters from the well-known protoplanetary disc HD 163296 with a suspected planet at $R\approx 86$~au as an example. By running gas and dust hydrodynamical simulations post-processed with dust radiative transfer calculations, we first find steady-state disc and planet parameters that reproduce ALMA continuum observations fairly well. For the same disc mass, but now allowing the planet to migrate in the simulation, we find that the planet undergoes runaway migration and reaches the inner disc in $\sim 0.2$ Myr. Further, decreasing the disc mass slows down planet migration, but it then also increases the dust's radial drift, thereby depleting the disc dust faster. We find that the opposing constraints of planet migration and dust drift require the disc mass to be at most $0.025~\msun$, must less massive than previously estimated, and for the dust to be porous rather than compact. We propose that similar analysis should be extended to other sources with suspected planetary companions.

Authors:Yayaati Chachan, Eve J. Lee

Abstract: Current measurements of planet population as a function of stellar mass show three seemingly contradictory signatures: close-in super-Earths are more prevalent around M dwarfs than FGK dwarfs; inner super-Earths are correlated with outer giants; and outer giants are less common around M dwarfs than FGK dwarfs. Here, we build a simple framework that combines the theory of pebble accretion with the measurements of dust masses in protoplanetary disks to reconcile all three observations. First, we show that cooler stars are more efficient at converting pebbles into planetary cores at short orbital periods. Second, when disks are massive enough to nucleate a heavy core at 5 AU, more than enough dust can drift in to assemble inner planets, establishing the correlation between inner planets and outer giants. Finally, while stars of varying masses are similarly capable of converting pebbles into cores at long orbital periods, hotter stars are much more likely to harbor more massive dust disks so that the giant planet occurrence rate rises around hotter stars. Our results are valid over a wide range of parameter space for a disk accretion rate that follows $\dot{M}_\star \sim 10^{-8}\,M_\odot\,{\rm yr}^{-1}(M_\star/M_\odot)^2$. We predict a decline in mini-Neptune population (but not necessarily terrestrial planets) around stars lighter than $\sim 0.3-0.5 \, M_\odot$. Cold giants ($\gtrsim$5 AU), if they exist, should remain correlated with inner planets even around lower mass stars.

Authors:Corrado Trigilio, Ayan Biswas, Paolo Leto, Grazia Umana, Innocenza Busa, Francesco Cavallaro, Barnali Das, Poonam Chandra, Miguel Perez-Torres, Gregg A. Wade, Cristobal Bordiu, Carla S. Buemi, Filomena Bufano, Adriano Ingallinera, Sara Loru, Simone Riggi

Abstract: In exoplanetary systems, the interaction between the central star and the planet can trigger Auroral Radio Emission (ARE), due to the Electron Cyclotron Maser mechanism. The high brightness temperature of this emission makes it visible at large distances, opening new opportunities to study exoplanets and to search for favourable conditions for the development of extra-terrestrial life, as magnetic fields act as a shield that protects life against external particles and influences the evolution of the planetary atmospheres. In the last few years, we started an observational campaign to observe a sample of nearby M-type stars known to host exoplanets with the aim to detect ARE. We observed YZ Ceti with the upgraded Giant Metrewave Radio Telescope (uGMRT) in band 4 (550-900 MHz) nine times over a period of five months. We detected radio emission four times, two of which with high degree of circular polarization. With statistical considerations we exclude the possibility of flares due to stellar magnetic activity. Instead, when folding the detections to the orbital phase of the closest planet YZ Cet b, they are at positions where we would expect ARE due to star-planet interaction (SPI) in sub-Alfvenic regime. With a degree of confidence higher than 4.37 sigma, YZ Cet is the first extrasolar systems with confirmed SPI at radio wavelengths. Modelling the ARE, we estimate a magnetic field for the star of about 2.4 kG and we find that the planet must have a magnetosphere. The lower limit for the polar magnetic field of the planet is 0.4 G.

Authors:O. Attia, V. Bourrier, J. -B. Delisle, P. Eggenberger

Abstract: The spin-orbit angle, or obliquity, is a powerful observational marker that allows us to access the dynamical history of exoplanetary systems. Here, we have examined the distribution of spin-orbit angles for close-in exoplanets and put it in a statistical context of tidal interactions between planets and their stars. We confirm the observed trends between the obliquity and physical quantities directly connected to tides, namely the stellar effective temperature, the planet-to-star mass ratio, and the scaled orbital distance. We further devised a tidal efficiency factor combining critical parameters that control the strength of tidal effects and used it to corroborate the strong link between the spin-orbit angle distribution and tidal interactions. In particular, we developed a readily usable formula to estimate the probability that a system is misaligned, which will prove useful in global population studies. By building a robust statistical framework, we reconstructed the distribution of the three-dimensional spin-orbit angles, allowing for a sample of nearly 200 true obliquities to be analyzed for the first time. This realistic distribution maintains the sky-projected trends, and additionally hints toward a striking pileup of truly aligned systems. The comparison between the full population and a pristine subsample unaffected by tidal interactions suggests that perpendicular architectures are resilient toward tidal realignment, providing evidence that orbital misalignments are sculpted by disruptive dynamical processes that preferentially lead to polar orbits. On the other hand, star-planet interactions seem to efficiently realign or quench the formation of any tilted configuration other than for polar orbits, and in particular for antialigned orbits.

Authors:M. Oosterloo, I. Kamp, W. van Westrenen, C. Dominik

Abstract: The abundances of CHNOS are crucial for the composition of planets. At the onset of planet formation, large amounts of these elements are stored in ices on dust grains in planet-forming disks. The evolution of this ice is affected by dynamical transport, collisional processes, and the formation and sublimation of ice. We aim to constrain the disk regions where these processes are fully coupled, and develop a flexible modelling approach that is able to predict the effects of these processes acting simultaneously on the CHNOS budgets of the dust in these regions. We compared timescales associated with these disk processes to constrain the disk regions where this approach is necessary, and developed the SHAMPOO code, which tracks the CHNOS abundances in the ice mantle of a single monomer dust particle, embedded in a larger aggregate and undergoing these processes simultaneously. The adsorption and photodesorption of monomer ices depend on the depth of the monomer in the aggregate. We investigated the effect of fragmentation velocity and aggregate filling factor on the amount of ice on monomers residing at r = 10 AU. The locations where disk processes are fully coupled depend on both grain size and ice species. Monomers embedded in aggregates with fragmentation velocities of 1 m/s are able to undergo adsorption and photodesorption more often compared to a fragmentation velocity of 5 m/s or 10 m/s. Aggregates with a filling factor of $10^{-3}$ are able to accumulate ice 22 times faster on average than aggregates with a filling factor of 1. As different grain sizes are coupled through collisions and the grain ice consists of multiple ice species, it is difficult to isolate the locations where disk processes are fully coupled, necessitating the development of the SHAMPOO code. The processing of ice may not be spatially limited to dust aggregate surfaces for either fragile or porous aggregates.

Authors:Sarah E. Moran, Kevin B. Stevenson, David K. Sing, Ryan J. MacDonald, James Kirk, Jacob Lustig-Yaeger, Sarah Peacock, L. C. Mayorga, Katherine A. Bennett, Mercedes López-Morales, E. M. May, Zafar Rustamkulov, Jeff A. Valenti, Jéa I. Adams Redai, Munazza K. Alam, Natasha E. Batalha, Guangwei Fu, Junellie Gonzalez-Quiles, Alicia N. Highland, Ethan Kruse, Joshua D. Lothringer, Kevin N. Ortiz Ceballos, Kristin S. Sotzen, Hannah R. Wakeford

Abstract: Planets orbiting M-dwarf stars are prime targets in the search for rocky exoplanet atmospheres. The small size of M dwarfs renders their planets exceptional targets for transmission spectroscopy, facilitating atmospheric characterization. However, it remains unknown whether their host stars' highly variable extreme-UV radiation environments allow atmospheres to persist. With JWST, we have begun to determine whether or not the most favorable rocky worlds orbiting M dwarfs have detectable atmospheres. Here, we present a 2.8-5.2 micron JWST NIRSpec/G395H transmission spectrum of the warm (700 K, 40.3x Earth's insolation) super-Earth GJ 486b (1.3 R$_{\oplus}$ and 3.0 M$_{\oplus}$). The measured spectrum from our two transits of GJ 486b deviates from a flat line at 2.2 - 3.3 $\sigma$, based on three independent reductions. Through a combination of forward and retrieval models, we determine that GJ 486b either has a water-rich atmosphere (with the most stringent constraint on the retrieved water abundance of H2O > 10% to 2$\sigma$) or the transmission spectrum is contaminated by water present in cool unocculted starspots. We also find that the measured stellar spectrum is best fit by a stellar model with cool starspots and hot faculae. While both retrieval scenarios provide equal quality fits ($\chi^2_\nu$ = 1.0) to our NIRSpec/G395H observations, shorter wavelength observations can break this degeneracy and reveal if GJ 486b sustains a water-rich atmosphere.

Authors:Antranik A. Sefilian, Roman R. Rafikov, Mark C. Wyatt

Abstract: High-resolution observations of several debris disks reveal structures such as gaps and spirals, suggestive of gravitational perturbations induced by underlying planets. Most existing studies of planet--debris disk interactions ignore the gravity of the disk, treating it as a reservoir of massless planetesimals. In this paper, we continue our investigation into the long-term interaction between a single eccentric planet and an external, massive debris disk. Building upon our previous work, here we consider not only the axisymmetric component of the disk's gravitational potential, but also the non-axisymmetric torque that the disk exerts on the planet (ignoring for now only the non-axisymmetric component of the disk \textit{self}-gravity). To this goal, we develop and test a semi-analytic `$N$-ring' framework that is based on a generalized (softened) version of the classical Laplace--Lagrange secular theory. Using this tool, we demonstrate that even when the disk is less massive than the planet, not only can a secular resonance be established within the disk that leads to the formation of a wide non-axisymmetric gap (akin to those observed in HD 107146, HD 92945, and HD 206893), but that the very same resonance also damps the planetary eccentricity via a process known as resonant friction. We also develop analytic understanding of these findings, finding good quantitative agreement with the outcomes of the $N$-ring calculations. Our results may be used to infer both the dynamical masses of gapped debris disks and the dynamical history of the planets interior to them, as we exemplify for HD 206893.