Interior and Surface Physics of Hot, Evaporating Rocky Exoplanets

到目前为止，已经发现了数千颗系外行星，而且更多的行星正在以惊人的速度被发现。其中大多数看起来很小（地球到超级地球大小），可能是岩石行星。然而，我们对后两颗行星的实际组成知之甚少；这一特性本身就很重要，而且对这些行星的形成和演化也有重要的影响。目前，研究它们组成的最有希望的方法是检查离它们的母恒星非常近的小行星：这些行星非常热，它们的表面预计会蒸发并逃逸到太空中，而JWST等即将到来的任务可以探测和分析逃逸的物质。然而，逃逸物质的组成和行星本身的组成之间的联系不是微不足道的：它以一种复杂的方式取决于行星内部和表面的物理和化学。该项目的目标是在广泛的行星质量和组成范围内详细研究这种物理现象，以便对蒸发和逃逸的表面物质的性质进行定量预测。将这些预测与即将到来的对此类热行星的观测结果进行比较，将为了解行星的真实组成提供重要的见解。这项工作将利用流体动力学、辐射物理学、地球物理学和地球化学，结合理论计算和数值模拟。

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.