Contributed Talk - Splinter Exoplanets

Thursday, 24 September 2020, 12:00   (virtual room D)

Shaping atmospheres of terrestrial exoplanets with interior-atmosphere feedback processes

Philipp Baumeister, Nicola Tosi, Jasmine MacKenzie, John Lee Grenfell, Mareike Godolt
Technische Universität Berlin, DLR Berlin

During the lifetime of a terrestrial planet, the evolution of its atmosphere is mainly driven by volcanic outgassing of volatiles from the planet’s interior. Outgassing rates are shaped by feedback processes in both the interior and the atmosphere, which are influenced by several factors, such as the initial mantle volatile content affecting convection in the mantle as well as the possibility to produce partial melts, and atmospheric pressure limiting the outgassing of volatiles from surface melts. We use a 1D parameterized convection model to simulate the evolution of H2O and CO2 outgassing into the atmospheres of terrestrial exoplanets, including feedback processes between interior and atmosphere, and utilize a chemical equilibrium model to describe the composition of the atmosphere over time. We are conducting an extensive parameter study to investigate a wide range of initial conditions, including, among others, the initial water content of the mantle, its redox state, the initial surface pressure of a primordial atmosphere, and the ratio between planetary core and mantle size. For planets with cores smaller than Earth’s, the atmosphere tends to be dominated by CO2, whereas H2O is the main atmosphere component for planets with larger cores. Furthermore, the total mass of the atmosphere remains largely constant throughout the evolution of the planet, regardless of the initial surface pressure.