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

TL;DR

This study models atmospheric mass loss in short-period exoplanets, like CoRoT-7b and Kepler-10b, showing they could be remnants of gas giants due to stellar radiation-driven escape processes.

Contribution

It combines atmospheric escape and thermal evolution models to simulate planetary evolution, considering different stellar XUV luminosity histories and applying them to specific exoplanets.

Findings

Both planets could originate from Jupiter-mass gas planets.

Stellar XUV evolution significantly influences initial planetary mass estimates.

Atmospheric escape mechanisms include thermal escape and Roche-lobe overflow.

Abstract

Short-period exoplanets potentially lose envelope masses during their evolution because of atmospheric escape caused by the intense 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 exploring 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.