Characterization of the interior of giant exoplanets with JWST transit observations and a coupled atmosphere-interior model

A major challenge for exoplanet science is to understand the connection between the atmosphere and the interior of exoplanets in order to understand their origins, structure and evolution [Fortney et al. ]. The observed chemical composition can be affected by the conditions in the deep atmosphere (intrinsic temperature, vertical mixing, interaction with a magma ocean,…), while measuring the atmospheric composition can help to break some degeneracies in the interior of exoplanets. Atmosphere-interior retrievals combining spectroscopic data with mass and radius measurements have been successfully applied to JWST observations of the warm Neptune WASP-107 b [Sing et al. 2024, Welbanks et al. 2024]. They revealed a high internal heat flux and large core, with some differences between the two studies (M_core=11.5+/-3 M_Earth for Sing et al. 2024 and M_core >22 M_Earth for Welbanks et al. 2024).

Here we use the coupled atmosphere-interior model called HADES [Wilkinson et al. 2024] to derive planetary properties (core mass, metallicity and intrinsic temperature) of giant exoplanets. First, we compare our results for WASP-107 b with previous measurements. Then we apply our model to a sample of giant exoplanets to derive trends with planetary mass and irradiation.

References

Fortney et al., JGR Planets, 2021

Sing et al., Nature, 2024

Welbanks et al., Nature, 2024

Wilkinson et al., A&A, 2024