Exoplanet HD209458b: inflated hydrogen atmosphere but no sign of evaporation

摘要: Many extrasolar planets orbit closely to their parent star. Their existence raises the fundamental problem of loss and gain in mass. For exoplanet HD209458b, reports on an unusually extended hydrogen corona a hot layer lower atmosphere seem support scenario atmospheric inflation by strong stellar irradiation. However, difficulties reconciling evaporation models with observations call for reassessment problem. Here, we use HST archive data report new absorption rate ~8.9% +/- 2.1% atomic during HD209458b transit, show that no sign could be detected exoplanet. We also evidence time variability HD209458 Lyman-a flux, was not accounted previous studies, which corrupted diagnostics. Mass rates thus far proposed literature range 5x(10^{10}-10^{11} g s^{-1}) must induce spectral signature line profile cannot found present analysis. Either unknown compensation effect is hiding expected feature or else mass neutrals from modest.