Abstract

Hycean worlds, characterised by their deep H2O oceans beneath H2-rich atmospheres, provide exciting new candidates for habitability amongst the exoplanet population. With their larger radii and atmospheric scale heights relative to terrestrial planets, Hycean worlds are promising candidates for atmospheric characterisation and biomarker detection. Internal structure modelling plays an important role in the characterisation of exoplanets based on their bulk properties, however degeneracies between possible interior compositions make this challenging. Atmospheric data, for instance with upcoming JWST observations, can help in breaking these degeneracies. We present our new internal structure model and discuss an application of the model to a candidate Hycean planet with recent atmospheric data. The possible compositions, surface conditions and ocean depths are investigated, and limits are placed on the conditions for habitability on this planet.