A tale of two exoplanets: the inflated atmospheres of the Hot Jupiters HD 189733 b and CoRoT-2 b

TL;DR

This study investigates the extended atmospheres of Hot Jupiters HD 189733 b and CoRoT-2 b through X-ray observations, revealing deep transits and potential atmospheric properties, and explores how exoplanets influence stellar activity evolution.

Contribution

It provides new X-ray observational data on exoplanet atmospheres and discusses their impact on stellar activity evolution, which is a novel approach in exoplanet research.

Findings

Deep X-ray transit of HD 189733 b indicating extended atmosphere

Preliminary X-ray observations of CoRoT-2 b from XMM-Newton

Exoplanets may influence the evolution of stellar activity through tidal interactions

Abstract

Planets in close orbits around their host stars are subject to strong irradiation. High-energy irradiation, originating from the stellar corona and chromosphere, is mainly responsible for the evaporation of exoplanetary atmospheres. We have conducted multiple X-ray observations of transiting exoplanets in short orbits to determine the extent and heating of their outer planetary atmospheres. In the case of HD 189733 b, we find a surprisingly deep transit profile in X-rays, indicating an atmosphere extending out to 1.75 optical planetary radii. The X-ray opacity of those high-altitude layers points towards large densities or high metallicity. We preliminarily report on observations of the Hot Jupiter CoRoT-2 b from our Large Program with XMM-Newton, which was conducted recently. In addition, we present results on how exoplanets may alter the evolution of stellar activity through tidal interaction.