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Astron. Astrophys. 355, 573-580 (2000)

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Search for an exosphere around 51 Pegasi B with ISO *

H. Rauer 1, D. Bockelée-Morvan 2, A. Coustenis 2, T. Guillot 3 and J. Schneider 2

1 DLR, Institute of Space Sensor Technology and Planetary Exploration, 12489 Berlin, Germany
2 Observatoire de Paris, 92195 Meudon, France
3 Observatoire de la Cote d'Azur, France

Received 1 July 1999 / Accepted 29 November 1999


The detection of absorption features in spectra of 51 Peg obtained during transit of its planet would provide a first clue on the physical nature of the planet. We have searched for signatures of an exosphere of the planet orbiting 51 Peg in the wavelength range from 2.39 µm to 3.5 µm and from 4.55 µm to 4.74 µm using SWS on ISO. Careful comparison of spectra taken during the transit of the planet with spectra obtained when the planet was not in the line-of-sight did not reveal any significant differences. We provide the S/N ratio and upper limits on the equivalent width of potential absorption lines in all wavelength bands. The upper limits on the equivalent width can be used for comparisons with predictions of the density of a potential exosphere of 51 Peg in future models.

Key words: techniques: spectroscopic – stars: atmospheres – stars: individual: 51 Peg B

* Based on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, the Netherlands and the United Kingdom) and with the participation of ISAS and NASA.

Send offprint requests to: H. Rauer (heike.rauer@dlr.de)

© European Southern Observatory (ESO) 2000

Online publication: March 9, 2000