Corpus ID: 117980531

"Osiris"(HD209458b), an evaporating planet

  title={"Osiris"(HD209458b), an evaporating planet},
  author={A. L. D. {\'E}tangs},
  journal={arXiv: Astrophysics},
Three transits of the planet orbiting the solar type star HD209458 were observed in the far UV at the wavelength of the HI Ly-alpha line. The planet size at this wavelength is equal to 4.3 R_Jup, i.e. larger than the planet Roche radius (3.6 R_Jup). Absorbing hydrogen atoms were found to be blueshifted by up to -130 km/s, exceeding the planet escape velocity. This implies that hydrogen atoms are escaping this ``hot Jupiter'' planet. An escape flux of >~ 10^10g/s is needed to explain the… Expand
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