The atmosphere-interior connection: What recent JWST observations revel about the interiors of Sub-Neptunes

Although several lines of evidence exist that Sub-Neptunes are frequently shrouded in hydrogen-dominated envelopes comprising up to a few percent of the planet’s total mass, the interior composition of Sub-Neptunes remains somewhat of a mystery. I will demonstrate that latest global chemical equilibrium models connecting Sub-Neptune interiors and hydrogen-dominated envelopes can be used to determine interior properties of Sub-Neptunes from atmospheric observations. One of the very first JWST spectra of a Sub-Neptune upper-atmosphere shows evidences indicating a hot interior and I will demonstrate that we can use its atmospheric chemical composition and mean molecular weight to probe the existence or absence of global magma ocean for such a sub-Neptune exoplanet.