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Astron. Astrophys. 332, 643-650 (1998)
Be stars in open clusters
III. A uvby
calibration for the
astrophysical parameters of Be stars
J. Fabregat and
J.M. Torrejón
Departamento de Astronomía, Universidad de
Valencia, E-46100 Burjassot, Valencia, Spain
Received 16 July 1997 / Accepted 17 December 1997
Abstract
We present linear relations between the equivalent widths of the
Balmer lines of Be stars and the anomalies in the uvby
photometric indices produced by continuum circumstellar emission. A
similar relation exists when the emission in the H
line is measured through the photometric index.
These relations have been used to elaborate an empirical
calibration of the uvby photometric
system to determine the intrinsic colours and indices, the relevant
astrophysical parameters and the absolute magnitude of the underlying
B star, valid for Be stars of spectral types earlier than B5. The
calibration is based on the study of 27 Be stars in 3 open clusters.
The proposed calibration procedure allows the determination of the
interstellar reddening with an accuracy of 0.033 mag. (rms) and the
absolute magnitude with an accuracy of 0.7 mag.
Our calibration independently confirms the previously known result that Be stars of spectral types in the range B0-B5 are overluminous by a mean of 0.3 mag. with respect to their absorption-line counterparts of the same spectral type.
Key words: stars: fundamental
parameters 
techniques:
photometric
stars: emission-line,
Be
open clusters and associations: general
Send offprint requests to: J. Fabregat (juan@pleione.uv.es)
Contents
- 1. Introduction
- 2. Relationship between photometric anomalies and Balmer line equivalent widths
- 3. The uvby calibration
- 4. Discussion
- 5. Conclusions
- Acknowledgements
- References
© European Southern Observatory (ESO) 1998
Online publication: March 23, 1998
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