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Astron. Astrophys. 332, 268-272 (1998)

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On the inner envelope of the Be star Cassiopeiae

Ph. Stee , F. Vakili , D. Bonneau and D. Mourard

Observatoire de la Côte d'Azur, Département FRESNEL, CNRS UMR 6528, 2130, route de l'Observatoire, Caussols, F-06460 St Vallier de Thiey, France

Received 19 November 1997 / Accepted 19 December 1997


We report the first spectrally-resolved observations of the Be star [FORMULA] Cas in the He I [FORMULA] and H [FORMULA] emission lines using the Grand Interféromètre à 2 Télescopes in the southern France. Milliarcsecond angular resolution measurements were carried in both lines and their neighbouring continuum during October and November 1993. The He I [FORMULA] and H [FORMULA] maximum emissions correspond respectively to 1.05 and 1.5 of the local continuum level. The interferometric baselines ranged from 15m to 51m on the sky which correspond to angular resolutions of 9 to 3 mas at He I [FORMULA] and 6.5 to 2 mas at H [FORMULA] wavelengths. We compare these values to predicted extents of H [FORMULA] and He I [FORMULA] components of the circumstellar gas from models of radiative transfer in these lines. We conclude that the emitting region must be smaller than 8.5 stellar radius in H [FORMULA] and close to 2.3 stellar radius in He I [FORMULA] which is, for He I [FORMULA], smaller than the nearby continuum extent. These results confirm [FORMULA] Cas basic parameters for this star obtained by Stee et al. on 1993 from their model constrained by GI2T observations in H [FORMULA] line.

Key words: stars: individual: fl Cas – circumstellar matter – stars: emission-line, Be – stars: mass-loss – techniques: interferometric

Send offprint requests to: Ph. Stee (stee@obs-nice.fr)

© European Southern Observatory (ESO) 1998

Online publication: March 10, 1998