Testing the paradigm of X-ray driven exoplanet evaporation with XMM+HST

HST observations show that two of the brightest transiting exoplanets areevaporating (HD209458b & HD189733b) and models suggest that the evolution ofclosein planets may be dominated by this mass loss. It is believed that theevaporation is driven by Xray irradiation of the planet by its parent star, buta lack of simultaneous measurements of irradiation and evaporation prevents ameaningful test of this model. We propose simultaneous XMMNewton and HSTobservations of three transits of the brightest Xray source, HD189733, in orderto test the paradigm of Xray driven evaporation and make a direct measurementof the efficiency of exoplanet evaporation. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]