Rocky super-Earths might have reducing interiors and atmospheres

Kurzfassung

In the last couple of years, the atmospheric characterization of selected super-Earths by observations started to become a reality. The first surprising results, including the non-detection of thick CO2 around the two innermost TRAPPIST-1 planets, showed the increased need for coupled interior-atmosphere models to understand potential evolutionary pathways for the atmosphere shaped amongst others by volcanic outgassing from the interior. Especially for super-Earth planets, it is still an open question, how the strength and chemistry of volcanic outgassing should vary depending on planetary mass and composition. One major factor, that directly influences the mantle redox state (and hence the expected abundances of various gases in the atmosphere), is the extraction of reducing iron into a metal core. However, massive super-Earths experience high pressures and a strong compressibility in their interior, which can impact the core formation and therefore mantle redox state of the planet, favouring a more reducing atmosphere (possibly even up to the extreme case of a secondary outgassed H2-dominated atmosphere). Preliminary results on core formation efficiency and their implications on the atmospheric evolution of massive super-Earths will be presented.