Early Evolution of Super-Earths: From Magma Ocean to Temperate Surface Conditions

2018
Recent discoveries of potentially temperate rocky planetsmotivate the better characterization of their surface conditions to predict where life could be detected in the universe. Early habitability of rocky planetsis determined by the cooling and solidification of the magma ocean(MO) stage. Indeed, the initial volatile content in the MO and the distance from the host star appear to play key-roles in the solidification of the MO, the extraction of the atmosphere, the existence of clouds and the formation (or not) of a primitive water ocean. However, the atmospheric properties strongly influence the planetary albedo, and therefore the amount of sunlight reaching the planetsurface. This in turn acts on the cooling rate of the planetand its atmosphere degassing. Using a coupled 1-D MO- atmosphere model, we systematically studied how the feedback between albedo, atmospheric composition, planetary surfacetemperature and clouds, influences the formation of a water ocean at the end of the initial rapid cooling stage of the planet. Here we extend this approach to different MO scenarios for super-Earths(ratio of planetary to core radius, volatile delivery) and discuss their potential habitability at the end of the rapid cooling stage.
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