Astron. Astrophys. 336, 980-985 (1998)

How thin B[e] supergiant disks can be?

Ph. Stee

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 29 January 1998 / Accepted 4 June 1998

Abstract

We investigate the shape of the envelope around B[e] supergiant stars using a model developed by Stee & Araùjo (1994) for Be stars. We obtain mass loss rates between and yr^-1 depending on mass flux variation from polar to equatorial regions. We find that winds from B[e] stars can be so dense that they become optically thick in the continuum, masking the photosphere of the central star. For mass loss rates larger than yr^-1 it is not possible to see the stellar photosphere even for pole-on B[e] stars. Using a two-component wind model driven by optically thin lines in the equatorial regions and optically thick lines in the polar regions, we obtain a relation between the geometry of the envelope and the total mass loss. We also put limits on the inclination angle () beyond which the stellar photosphere is masked. Finally, this study seems to discard "wind-compressed disks" (WCD) models as a possible senario for B[e] supergiant envelopes.

Key words: circumstellar matter stars: emission-line, Be stars: mass-loss stars: supergiants

Send offprint requests to: stee@obs-nice.fr

This article contains no SIMBAD objects.

Contents

• 1. Introduction
• 2. A model for B[e] stars
  • 2.1. Main hypothesis
  • 2.2. Different envelope geometries
• 3. The continuum source function
• 4. Results
• 5. Discussion
  • 5.1. Do we see photospheric features on B[e] stars?
  • 5.2. Effect of the terminal velocity of the wind
  • 5.3. Effect of the mass flux
• 6. Conclusion
• Acknowledgements
• References

© European Southern Observatory (ESO) 1998

Online publication: July 27, 1998
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