Earth and Planetary Astrophysics (astro-ph.EP)

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.

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.

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.

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.