“Extreme planet atmospheric escape: current standing and future observability”. Luca Fossati (Space Research Institute, Austrian Academy of Sciences, Austria)

Planets in short-period orbits provide a unique opportunity to directly study atmospheric escape, which is a phenomenon having a profound impact on our understanding of the observed exoplanet demographics. Among all planets known to have an escaping atmosphere, those undergoing extreme mass loss are key: their escape may be representative of young planets, at a time when atmospheric escape matters most. I will review results obtained from the analysis of Hubble Space Telescope observations, particularly those of the extreme hot Jupiters WASP-12b, WASP-13b, and WASP-18b. I will then show how planet atmospheric escape may be at the origin of the correlation between the chromospheric activity of stars hosting hot Jupiters and the planets’ surface gravity. I will finally show how planets orbiting early-type stars might become of crucial importance in the near future and how their escaping atmospheres can be observationally studied.