Characterising the interior structures and atmospheres of Multiplanetary systems

L. Acuña (1) , T. Lopez (1) , M. Deleuil (1) , Olivier Mousis (1) , Emmanuel Marcq (2) , T. Morel (3) , A. Santerne (1)

1 LAM - Laboratoire d'Astrophysique de Marseille
2 PLANETO - LATMOS
3 STAR - Space Sciences, Technologies and Astrophysics Research Institute

The modelling of the internal structures of super-Earths and sub-Neptunes gives a valuable insight into their formation history and possible atmospheres. We present a planet model where the interior is coupled with the atmosphere within a Bayesian retrieval scheme. We take into account water in all its possible phases, including steam and supercritical phases, which is necessary for systems with a wide range of stellar irradiations. Our interior-atmosphere model calculates the compositional and atmospheric parameters, such as Fe and water content, surface pressures, scale heights and albedos. We analyse the multiplanetary systems K2-138 and TRAPPIST-1. From their individual composition, we derive a global increasing trend on the water content with increasing distance from the star in the inner region of the systems, while the planets in the outer region present a constant water mass fraction. This trend reveals the possible effects of migration, formation location and atmospheric mass loss during their formation history.

Domaines: Planète et Univers [physics]

L. Acuña, T. Lopez, M. Deleuil, Olivier Mousis, Emmanuel Marcq, et al.. Characterising the interior structures and atmospheres of Multiplanetary systems. SF2A-2021: Proceedings of the Annual meeting of the French Society of Astronomy and Astrophysics, Jun 2021, On Line, France. pp.355-358. ⟨insu-03688519⟩