Towards a new era in giant exoplanet characterisation by Simon Müller et al. on Thursday 24 November

Determining the composition of giant exoplanets is crucial for understanding

their origin and evolution. However, the planetary bulk composition is not

measured directly but must be deduced from a combination of mass-radius

measurements, knowledge of the planetary age and evolution simulations.

Accurate determinations of stellar ages, mass-radius, and atmospheric

compositions from upcoming missions can significantly improve the determination

of the heavy-element mass in giant planets. In this paper, we first demonstrate

the importance of an accurate age measurement, as expected from Plato, in

constraining the planetary properties. Well-determined stellar ages can reduce

the bulk-metallicity uncertainty up to about a factor of two. We next infer the

bulk metallicity of warm giants from the Ariel mission reference sample and

identify the Ariel high-priority targets for which a measured atmospheric

metallicity can clearly break the degeneracy in the inferred composition. We

show that knowledge of the atmospheric metallicity can broadly reduce the

bulk-metallicity uncertainty by a factor of four to eight. We conclude that the

accurate age determination from Plato and atmospheric measurements by Ariel and

the James Webb Space Telescope will play a key role in revealing the

composition of giant exoplanets.

arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.05468v2