Atmospheric mass-loss and evolution of short-period exoplanets: The examples of CoRoT-7b and Kepler-10b

Abstract

Short-period exoplanets potentially lose envelope masses during their evolution because of atmospheric escape caused by the intense X-ray and extreme UV (XUV) radiation from their host stars. We develop a combined model of atmospheric mass-loss calculation and thermal evolution calculation of a planet to simulate its evolution and explore the dependences on the formation history of the planet. Thermal atmospheric escape as well as the Roche lobe overflow contributes to mass-loss. The maximum initial planetary model mass depends primarily on the assumed evolution model of the stellar XUV luminosity. We adapt the model to CoRoT-7b and Kepler-10b to explore the evolution of both planets and the maximum initial mass of these planets. We take the recent X-ray observation of CoRoT-7 into account and explore the effect of different XUV evolution models on the planetary initial mass. Our calculations indicate that both hot super-Earths could be remnants of Jupiter-mass gas planets. © 2013 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.