The harsh environment where exoplanets live

Abstract

AbstractThe X‐ray and Extreme Ultraviolet (XUV) actvity of the Sun has determined important effects on the planets around it. In particular, high doses of X‐rays, flares, and coronal mass ejections (CMEs) combined with masses and sizes of the planets and the shielding action of the planetary magnetic fields have determined the diverse habitability of rocky planets like Venus, Earth, and Mars. In exoplanetary systems, the same could apply, especially in those stars with close‐in planets like hot Jupiter's or Earth analogs around M dwarfs. These planets live in the harsh environment of the hot coronal fringes. This has a consequence on the evaporation and the photochemistry of the upper atmospheres of such planets. Furthermore, phenomena related to gravitational and magnetic interaction between stars and close‐in planets could be at work. Effects due to star–planet interaction could be the transfer of rotational momentum between planet and star, magnetic interaction between the fields of planet and star that could potentially lead to flares in the outer corona, evaporation with the formation of a cloud of planetary gas around the star, and accretion onto the star itself. In this review, I will report on the search for such phenomena at XUV bands with X‐ray observatories like XMM‐Newton.