Atmospheric mass loss of extrasolar planets orbiting magnetically active host stars

TL;DR

This study investigates how magnetic stellar activity causes high-energy irradiation that heats and evaporates the atmospheres of close-in exoplanets, leading to potential mass loss, based on XMM-Newton observations of four active host stars.

Contribution

It provides new measurements of X-ray luminosities of active stars hosting exoplanets and estimates the upper limits of atmospheric mass loss due to stellar irradiation.

Findings

Host stars exhibit high X-ray luminosities, exceeding solar levels.

The planets receive intense XUV irradiation, greater than that of typical hot Jupiters.

Upper limits on planetary atmospheric mass loss are derived from observed stellar emissions.

Abstract

Magnetic stellar activity of exoplanet hosts can lead to the production of large amounts of high-energy emission, which irradiates extrasolar planets, located in the immediate vicinity of such stars. This radiation is absorbed in the planets' upper atmospheres, which consequently heat up and evaporate, possibly leading to an irradiation-induced mass-loss. We present a study of the high-energy emission in the four magnetically active planet-bearing host stars Kepler-63, Kepler-210, WASP-19, and HAT-P-11, based on new XMM-Newton observations. We find that the X-ray luminosities of these stars are rather high with orders of magnitude above the level of the active Sun. The total XUV irradiation of these planets is expected to be stronger than that of well studied hot Jupiters. Using the estimated XUV luminosities as the energy input to the planetary atmospheres, we obtain upper limits for the total mass loss in these hot Jupiters.