Second, evaporation of Hot-Jupiters is studied and compared with population of exoplanets. The relation also indicates the possibility of Roche-lobe overflow at sub-Jupiter mass regime regime for close-in exoplanets. A runaway property of the mass-loss evolution is shown in the relation diagrams.
First, basic properties of the mass-loss evolution are described using envelope mass - planetary radius relationships which combine Jupiter mass regime with Super-Earth regime. The model is applied to the mass-loss of Hot-Jupiters and low-density Super-Earths which have envelopes of hydrogen and helium. The Roche-lobe overflow is also taken into account as a mass-loss process. An semi-analytical model of the radiation-recombination limited escape is developed and included in the model, as well as the energy-limited escape. We develop a numerical model to simulate an evolution of planets considering thermal cooling and the mass-loss. We focus on its effects on population and composition of exoplanets. Close-in exoplanets might have lost substantial masses during their evolution due to atmospheric escape of upper atmosphere heated by intense stellar XUV (X-ray and EUV) radiation and dynamical Roche-lobe overflow.
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