Evaporation of extrasolar planets

Abstract

Atomic hydrogen escaping from the extrasolar giant planet HD209458b provides the largest observational signature ever detected for an extrasolar planet atmosphere. In fact, the upper atmosphere of this planet is evaporating. Observational evidences and interpretations coming from various models are reviewed. Implications for exoplanetology are discussed.Comment: 12 pages, 4 figures. To appear in the proceedings of the Les Houches Winter School "Physics and Astrophysics of Planetary Systems" (EDP Sciences: EAS Publications Series