Habitability of Earth-like stagnant-lid planets around main sequence stars

24. Mai 2018

Ein Vortrag von Mareike Godolt (DLR Berlin, Deutschland) im Rahmen der IWF-Seminarreihe Frühjahr/Sommer 2018

Understanding under which circumstances rocky planets may be habitable is one of the major quests in exoplanetary science. Since it is unknown which percentage of rocky extrasolar planets will have plate tectonics and thereby a long-term carbonate silicate cycle, we aim at understanding under which conditions planets in a stagnant-lid regime, hence without plate tectonics, may support habitable surface conditions. By studying the interior and atmosphere evolution accounting for secondary outgassing we furthermore investigate whether a water reservoir may be rebuilt after the relatively long, high luminous pre-main sequence phase of M dwarf stars.

We compute the boundaries of the habitable zone around M, K, G, and F dwarf stars with a 1D cloud-free radiative-convective climate model accounting for the outgassing history of CO2 and H2O from an interior evolution model for different interior compositions as described in Tosi et al. 2017. We show that the inner edge of the habitable zone is mainly depends on the stellar irradiation, while the outer edge shows a strong dependence on the outgassing history of CO2. A build-up of a secondary water reservoir for planets around M dwarf stars after the high luminosity pre-main sequence phase may only be possible as long as some water has been retained within the mantle.