11:30 am–12:00 pm ERC 401
Simulated Evolution of Sub-Neptune Exoplanets: Coupling the Magma Ocean and H/He Envelope
Advisor: Leslie Rogers
Sub-Neptune exoplanets are the most commonly discovered population of exoplanets in the last 25 years, yet the solar system contains no direct analog in this mass-radius regime. Sub-Neptunes are characterised by their rocky cores and large hydrogen/helium envelopes, approximately 2-20 Earth masses and 2-4 Earth radii in size. Their hot rocky cores are molten after planet formation and capable of dissolving large amounts of hydrogen into their magma oceans. We perform 1D simulations of sub-Neptune H/He envelopes and introduce subroutines for dynamical core-atmosphere mass exchange via the dissolution/out-gassing of atmospheric hydrogen into/from the magma ocean of the rocky core. We constrain the mass of this dissolved hydrogen reservoir and present planet evolution tracks demonstrating the timescales surrounding the out-gassing of hydrogen, the solidification of the magma ocean, the growth of atmospheric mass, and the effect of this additional hydrogen on planet radius. We find the dissolved hydrogen reservoir to have first order effects on planet structure and radius evolution even at >1 billion year timescales, demonstrating the importance of this mechanism for future studies of sub-Neptune exoplanets.