X-raying CoRoT2a comma the most active planet host-star known to date

Stellar activity plays a key role in the evolution of planetary systems. HotJupiters around active stars are immersed in intense highenergy radiationfields and particle emission. In particular hydrodynamic blowoff of the outerplanetary atmosphere should occur, which leads to larger Xray radii of hotJupiters and to deeper eclipse depths at Xray wavelengths, which should beobservable with XMMNewton. The extrasolar planet system CoRoT2 harbors themost active planet hoststar known to date; its unique properties actually allowto perform sensitive Xray observations of planetary transits and study suchblowoff phenomena. We simultaneously study the Xray and optical variability ofCoRoT2 by observing 15 transits distributed over almost eight stellar rotations. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]