Interior and Surface Physics of Hot, Evaporating Rocky Exoplanets

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Thousands of exoplanets have been discovered so far, and more are being identified at breakneck speed. A majority of these appear to be small (Earth to super-Earth sized), presumably rocky planets. However, we have very little information about the actual compositions of the latter planets; a property which is of fundamental interest in itself, and also has critical implications for the formation and evolution of these planets. Currently, the most promising way to investigate their compositions is to examine small planets orbiting very close to their parent stars: these planets are so hot that their surfaces are expected to be evaporating and escaping into space, and upcoming missions such as JWST can detect and analyse the escaping material. However, the connection between the composition of the escaping material and that of the planet itself is not trivial: it depends in a complicated fashion on the interior and surface physics and chemistry of the planets. The goal of this project is to investigate in detail this physics for a broad range of planetary masses and compositions, in order to make quantitative predictions about the properties of the surface material that evaporates and escapes. Comparison of these predictions with upcoming observations of such hot planets will then lend vital insights into the true planetary compositions. The work will draw on hydrodynamics, radiation physics, geophysics and geochemistry, married to theoretical calculations and numerical simulations.