EVAPORATION OF CLOSE-IN GIANT PLANETS DUE TO INTENSE XUV RADIATION

Abstract. Astrophysical observations of young stars indicate much larger X-ray and EUV fluxes than stars with the age of our present Sun. Because of this one can expect that during and after giant planet formation the early high radiation flux of a parent star in the short wavelengths will have great impact on atmospheric loss from such a planet. We solve the system of hydrodynamic equations for a hydrogen atmosphere to study thermal escape processes from a “Hot Jupiter”. It is shown that HD209458b might have lost about 4 % of its present mass due to thermal atmospheric escape