Astron. Astrophys. 324, 597-605 (1997)

Continuum IR emission of Be star wind-compressed discs

John M. Porter

¹ Astrophysics, School of Electrical Engineering, Electronics and Physics, Liverpool John Moores University, Byrom Street, Liverpool L3 3AF, UK

Received 20 November 1996 / Accepted 14 January 1997

Abstract

A prescription for the density of a wind compressed disc (WCD) is given and the IR emission of the disc is calculated. The prescription enables emission from WCDs to be calculated simply without recourse to full 2 -dimensional (2 -D) modelling of rotating radiatively driven winds. It is shown that the standard WCD model is incapable of representing observed Be star discs.

As a guide for future research, various addenda to the WCD model are considered: internal density structure of the disc, decoupling of the matter and radiation fields in the wind and finally magnetic fields. Of these, it is only a magnetic field which may be sufficient as a suffix to bring the WCD model into line with observations. The magnetic field strength must be tens of gauss to begin to reproduce observations.

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

Contents

• 1. Introduction
• 2. Wind compressed disc model
  • 2.1. Wind structure
  • 2.2. Disc density and structure
    • 2.2.1. Inner disc
    • 2.2.2. Outer disc
    • 2.2.3. Example calculation
• 3. IR continuum emission from the WCD
• 4. Simple addenda to the WCD model
  • 4.1. Internal structure in the disc
  • 4.2. Wind decoupling
  • 4.3. Magnetic fields
• 5. Discussion
• 6. Conclusion
• Acknowledgements
• References

© European Southern Observatory (ESO) 1997

Online publication: May 26, 1998

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