Gravitational atmospheric tides as a probe of Titan's interior: Application to Dragonfly

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1. Proche Pas pertinent

   Saturn's Interior After the Cassini Grand Finale

   J. J. Fortney, B. Militzer, C. R. Mankovich et al. · 2023 · Astrophysique terrestre et planétaire · Résumé IA disponible

   Résumé scientifique

   We present a review of Saturn's interior structure and thermal evolution, with a particular focus on work in the past 5 years. Data from the Cassini mission, including a precise determination of the gravity field from the Grand Finale orbits, and the still ongoing identification of ring wave features in Saturn's C-ring tied to seismic modes in the planet, have led to dramatic advances in our understanding of Saturn's structure. Models that match the gravity field suggest that differential rotation, as seen in the visible atmosphere, extends down to at least a depth of 10,000 km (1/6$^{\rm th}$ the planet's radius). At greater depths, a variety of different investigations all now point to a d…

2. Apparenté Pas pertinent

   Tidal Distortions as a Bottleneck on Constraining Exoplanet Compositions

   David Berardo, Julien de Wit · 2023 · ApJ 941 155 (2022) · Résumé IA disponible

   Résumé scientifique

   Improvements in the number of confirmed planets and the precision of observations imply a need to better understand subtle effects that may bias interpretations of exoplanet observations. One such effect is the distortion of a short period planet by its host star, affecting its derived density. We extend the work of Burton et al., Correia, and others, using a gravitational potential formulation to a sample of nearly 200 planets with periods less than 3 days. We find five planets exhibiting density variations of >10% and as many as 20 planets with deviations >5%. We derive an analytic approximation for this deviation as a function of the orbital period, transit depth, and mass ratio between t…

3. Apparenté Pas pertinent

   Identifying deformed exoplanets with JWST and Ariel: A target selection metric for phase curve observations

   Vanesa Ramirez, Yamila Miguel, Billy Edwards et al. · 2026 · Astrophysique terrestre et planétaire · Résumé IA disponible

   Résumé scientifique

   The shape of an exoplanet encodes fundamental information about its internal structure. For close-in giant planets, strong stellar tidal forces induce measurable deformations that can be probed through high-precision photometry. These deformations are quantified by the fluid Love numbers, which characterise a planet's response to external perturbations and are directly linked to its internal density distribution. In this work, we assess the potential of JWST and the future Ariel mission to constrain the Love numbers of hot Jupiters through full-orbit phase curve observations. To identify the most promising targets for this science case, we introduce a new detection metric, the deformation me…

4. Apparenté Pas pertinent

   JWST molecular mapping and characterization of Enceladus' water plume feeding its torus

   G. L. Villanueva, H. B. Hammel, S. N. Milam et al. · 2023 · Astrophysique terrestre et planétaire · Résumé IA disponible

   Résumé scientifique

   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 t…

5. Apparenté Pas pertinent

   Absolute densities in exoplanetary systems: photodynamical modelling of Kepler-138

   J. M. Almenara, R. F. Díaz, C. Dorn et al. · 2018 · Astrophysique terrestre et planétaire · Résumé IA disponible

   Résumé scientifique

   In favourable conditions, the density of transiting planets in multiple systems can be determined from photometry data alone. Dynamical information can be extracted from light curves, providing modelling is done self-consistently, i.e. using a photodynamical model, which simulates the individual photometric observations instead of the more generally used transit times. We apply this methodology to the Kepler-138 planetary system. The derived planetary bulk densities are a factor of 2 more precise than previous determinations, and we find a discrepancy in the stellar bulk density with respect to a previous study. This leads, in turn, to a discrepancy in the determination of masses and radii o…

6. Apparenté Pas pertinent

   Detection of TiO and VO in the atmosphere of WASP-121b and Evidence for its temporal variation

   Qinglin Ouyang, Wei Wang, Meng Zhai et al. · 2023 · Astrophysique terrestre et planétaire · Résumé IA disponible

   Résumé scientifique

   We report the transit observations of the ultra hot Jupiter WASP-121b using the Goodman High Throughput Spectrograph (GHTS) at the 4-meter ground-based telescope Southern Astrophysical Research Telescope (SOAR), covering the wavelength range $502-900$ nm. By dividing the target and reference star into 19 spectroscopic passbands and applying differential spectrophotometry, we derive spectroscopic transit light curves and fit them using Gaussian process framework to determine transit depths for every passbands. The obtained optical transmission spectrum shows a steep increased slope toward the blue wavelength, which seems to be too steep to be accounted for by the Rayleigh scattering alone. We…

7. Apparenté Pas pertinent

   Uncovering the true periods of the young sub-Neptunes orbiting TOI-2076

   Hugh P. Osborn, Andrea Bonfanti, Davide Gandolfi et al. · 2022 · Astrophysique terrestre et planétaire · Résumé IA disponible

   Résumé scientifique

   Context: TOI-2076 is a transiting three-planet system of sub-Neptunes orbiting a bright (G = 8.9 mag), young ($340\pm80$ Myr) K-type star. Although a validated planetary system, the orbits of the two outer planets were unconstrained as only two non-consecutive transits were seen in TESS photometry. This left 11 and 7 possible period aliases for each. Aims: To reveal the true orbits of these two long-period planets, precise photometry targeted on the highest-probability period aliases is required. Long-term monitoring of transits in multi-planet systems can also help constrain planetary masses through TTV measurements. Methods: We used the MonoTools package to determine which aliases to follo…

8. Apparenté Pas pertinent

   Saltire -- A model to measure dynamical masses for high-contrast binaries and exoplanets with high-resolution spectroscopy

   Daniel Sebastian, Amaury H. M. J. Triaud, Matteo Brogi · 2023 · Astrophysique terrestre et planétaire · Résumé IA disponible

   Résumé scientifique

   High-resolution cross-correlation methods are widely used to discover and to characterise atomic and molecular species in exoplanet atmospheres. The characteristic cross-correlation signal is typically represented as a function of the velocity of the system, and the semi-amplitude of the planet's orbit. We present Saltire, a fast and simple model that accurately reproduces the shape of such cross-correlation signals, allowing a direct fit to the data by using a minimum set of parameters. We show how to use this model on the detection of atmospheric CO in archival data of the hot Jupiter tau Bootis b, and how Saltire can be used to estimate the semi-amplitude and rest velocity of high brightn…