Evaporation of the planet HD189733b observed in HI Lyman-alpha
A. Lecavelier des Etangs,David Ehrenreich,Alfred Vidal-Madjar,Gilda E. Ballester,Jean-Michel Desert,Roger Ferlet,G. Hebrard,David K. Sing,K.-O. Tchakoumegni,Stéphane Udry +9 more
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In this paper, a transit of the extrasolar planet HD189733b in HI Lyman-alpha and in a few other lines in the ultraviolet with HST/ACS was detected.Abstract:
We observed three transits of the extrasolar planet HD189733b in HI Lyman-alpha and in a few other lines in the ultraviolet with HST/ACS, in the search for atmospheric signatures. We detect a transit signature in the Lyman-alpha light curve with a transit depth of 5.05 +/- 0.75 %. This depth exceeds the occultation depth produced by the planetary disk alone at the 3.5-sigma level (statistical). Other stellar emission lines are less bright, and, taken individually, they do not show the transit signature, while the whole spectra redward of the Lyman-alpha line has enough photons to show a transit signature consistent with the absorption by the planetary disk alone. The transit depth's upper limits in the emission lines are 11.1% for OI at 1305A and 5.5% for CII at 1335A. The presence of an extended exosphere of atomic hydrogen around HD189733b producing 5% absorption of the full unresolved Lyman-alpha line flux shows that the planet is losing gas. The Lyman-alpha light curve is well-fitted by a numerical simulation of escaping hydrogen in which the planetary atoms are pushed by the stellar radiation pressure. We constrain the escape rate of atomic hydrogen to be between 10^9 and 10^{11} g/s and the ionizing extreme UV flux between 2 and 40 times the solar value (1-sigma), with larger escape rates corresponding to larger EUV flux. The best fit is obtained for dM/dt=10^{10} g/s and an EUV flux F_{EUV}=20 times the solar value. HD189733b is the second extrasolar planet for which atmospheric evaporation has been detected.read more
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A closely packed system of low-mass, low-density planets transiting Kepler-11
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DISEQUILIBRIUM CARBON, OXYGEN, AND NITROGEN CHEMISTRY IN THE ATMOSPHERES OF HD 189733b AND HD 209458b
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The Role of Core Mass in Controlling Evaporation: The Kepler Radius Distribution and the Kepler-36 Density Dichotomy
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Journal ArticleDOI
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TL;DR: In this article, the authors used time series spectra obtained during two transit events to determine the wavelength dependence of the planetary radius and measure the exoplanet's atmospheric transmission spectrum for the first time over this wavelength range.
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How thermal evolution and mass-loss sculpt populations of super-earths and sub-neptunes: application to the kepler-11 system and beyond
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Evaporation of extrasolar planets
TL;DR: Atomic hydrogen escaping from the extrasolar giant planet HD209458b provides the largest observational signature ever detected for an extrasolar planet atmosphere as discussed by the authors, in fact, the upper atmosphere of this planet is evaporating.