Seminar – Caroline Dorn

Speaker: CAROLINE DORN, ETH ZURICH

Title: Hidden water in magma oceans

Abstract:
Over the past years, there has been huge progress in our understanding of the bulk properties of sub-Neptune exoplanets. Because hot and close-in planets are abundant in the exoplanet population, phase transitions in the interiors of small, dominantly rocky planets have come into sharper focus. Here, we use coupled structural models of the interior and atmosphere of up to super-Earth-sized exoplanets to explore the effect of water partitioning into the interiors of rocky planets inside the runaway greenhouse transition and calculate the effect on the total radius of planets compared to recent models that ignore this effect. The two end-member assumptions lead to a deviation in total planet radius on the order of 5-10%, which is within current accuracy limits for individual systems and will be statistically testable with next-generation transit surveys. In consequence, the inferred water content for a given observed radius of a specific planet may be underestimated by up to two orders of magnitude if volatile partitioning between planetary sub-reservoirs is not accounted for.