Cold H I in IRC +10216
DEMIRM, UMR 8540, Observatoire de Paris, 61 av. de l'Observatoire, 75014 Paris, France
2 ARPEGES, UMR 8644, Observatoire de Paris, 5 place J. Janssen, 92195 Meudon Cedex, France e-mail: Eric.Gerard@obspm.fr
Corresponding author: T. Le Bertre, Thibaut.LeBertre@obspm.fr
Accepted: 6 September 2001
With the recently refurbished Nançay Radiotelescope we have observed the H I 21 cm line in the direction of IRC +10216, a typical high mass-loss carbon star. We found H I in absorption indicating that the expanding circumstellar gas may reach very low temperatures ( K). The atomic gas could be the product of the photo-dissociation of molecular hydrogen in the outer envelope or result from a previous phase ( years ago) of mass loss when the star had a higher effective temperature than now.
Key words: stars: circumstellar matter / stars: mass-loss / stars: AGB and post-AGB / radio lines: stars
© ESO, 2001