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An extended upper atmosphere around the extrasolar planet HD209458b

Nature volume 422, pages 143146 (13 March 2003) | Download Citation

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Abstract

The planet in the system HD209458 is the first one for which repeated transits across the stellar disk have been observed1,2. Together with radial velocity measurements3, this has led to a determination of the planet's radius and mass, confirming it to be a gas giant. But despite numerous searches for an atmospheric signature4,5,6, only the dense lower atmosphere of HD209458b has been observed, through the detection of neutral sodium absorption7. Here we report the detection of atomic hydrogen absorption in the stellar Lyman α line during three transits of HD209458b. An absorption of 15 ± 4% (1σ) is observed. Comparison with models shows that this absorption should take place beyond the Roche limit and therefore can be understood in terms of escaping hydrogen atoms.

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References

  1. 1.

    , , & A transiting “51 Peg-like” planet. Astrophys. J. 529, L41–L44 (2000)

  2. 2.

    , , & Detection of planetary transits across a Sun-like star. Astrophys. J. 529, L45–L48 (2000)

  3. 3.

    et al. The spectroscopic orbit of the planetary companion transiting HD 209458. Astrophys. J. 532, L55–L58 (2000)

  4. 4.

    & A search for transit effects in spectra of 51 Pegasi and HD 209458. Proc. Astron. Soc. Pacif. 112, 1421–1425 (2000)

  5. 5.

    , , , & Search for an exosphere around 51 Pegasi B with ISO. Astron. Astrophys. 355, 573–580 (2000)

  6. 6.

    et al. Search for spectroscopical signatures of transiting HD 209458b's exosphere. Astron. Astrophys. 371, 260–266 (2001)

  7. 7.

    , , & Detection of an extrasolar planet atmosphere. Astrophys. J. 568, 377–384 (2002)

  8. 8.

    Evolution of the solar lyman alpha flux during four consecutive years. Sol. Phys. 40, 69–86 (1975)

  9. 9.

    et al. in Proc. Symp. SOHO 11, From Solar Min to Max: Half a Solar Cycle with SOHO (ed. Wilson, A.) 219–222 (ESA SP-508, ESA Publications Division, Noordwijk, 2002)

  10. 10.

    The spatial distribution of Lyman alpha on the Sun. Astrophys. J. 187, 369–375 (1974)

  11. 11.

    Evolutionary processes in close binary systems. Annu. Rev. Astron. Astrophys. 9, 183–208 (1971)

  12. 12.

    Cumming, A., Marcy, G. W., Butler, R. P. & Vogt, S. S. The statistics of extrasolar planets: Results from the Keck survey. Preprint astro-ph/0209199 available at 〉 (2002).

  13. 13.

    , , & An extrasolar planet that transits the disk of its parent star. Nature 421, 507–509 (2003)

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Acknowledgements

This work is based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc. We thank M. Lemoine, L. Ben Jaffel, C. Emerich, P. D. Feldman and J. McConnell for comments, J. Herbert and W. Landsman for conversations on STIS data reduction, and J. Valenti for help in preparing the observations.

Author information

Affiliations

  1. *Institut d'Astrophysique de Paris, CNRS/UPMC, 98bis boulevard Arago, F-75014 Paris, France

    • A. Vidal-Madjar
    • , A. Lecavelier des Etangs
    • , J.-M. Désert
    • , R. Ferlet
    •  & G. Hébrard
  2. †Lunar and Planetary Laboratory, University of Arizona, 1040 E. 4th St., Rm 901, Tucson, Arizona 85721-0077, USA

    • G. E. Ballester
  3. ‡Observatoire de Genève, CH-1290 Sauverny, Switzerland

    • M. Mayor

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The authors declare that they have no competing financial interests.

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Correspondence to A. Vidal-Madjar.

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https://doi.org/10.1038/nature01448

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