Volume 397, Number 3, January III 2003
|Page(s)||L17 - L21|
|Published online||21 January 2003|
Letter to the Editor
The H I emission profile of RS Cnc
GEPI, FRE 2459, Observatoire de Paris, 5 place J. Janssen, 92195 Meudon Cedex, France
2 LERMA, FRE 2460, Observatoire de Paris, 61 Av. de l'Observatoire, 75014 Paris, France
Corresponding author: E. Gérard, Eric.Gerard@obspm.fr
Accepted: 2 December 2002
The H I line at 21 cm has been detected in the direction of the S-type AGB star RS Cnc with the Nançay Radio Telescope (NRT). The profile is composite and similar to the CO rotational line profiles. It is composed of a narrow rectangular component overimposed on a wider Gaussian one, both centred on the stellar radial velocity. The narrow component has a width of 4 km s-1 and is unresolved (with the NRT beam size of in α). The Gaussian component has a width (FWHM) of 12 km s-1 and seems resolved by the NRT. These components trace at least 2 different episodes of mass loss by RS Cnc. We argue that the atomic hydrogen responsible for the narrow rectangular profile was likely formed in the stellar atmosphere which could thus be devoid of molecular hydrogen, although we cannot strictly exclude that up to 25% may have been produced by photodissociation of H2. As predicted 20 years ago by Glassgold & Huggins, such a situation should be common to giants with stellar effective temperature larger than 2500 K. This property is relevant to the atmospheric structure of these sources and probably also to the characteristics of their winds.
Key words: stars: circumstellar matter / stars: mass-loss / stars: individual: RS Cnc / stars: AGB and post-AGB / radio lines: stars
© ESO, 2003
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.