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The number of Be stars compared with the number of B stars, taking into account the specific physical characteristics of Be stars

Published online by Cambridge University Press:  26 May 2016

D. Briot  and
J. Zorec
D. Briot
Affiliation:
Observatoire de Paris, 61 Avenue de l'Observatoire, 75014 Paris
J. Zorec
Affiliation:
Institut d'Astrophysique de Paris, 98bis Boulevard Arago, 75014 Paris

Extract

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It is very important for the understanding of the Be phenomenon, and particularly for locating a possible Be phase in the evolutionary track of B stars, to accurately determine the proportion of Be stars among all B stars. This type of study was already made several times in the past. Results obtained generally show a maximum Be frequency around spectral type B2 then a decrease towards late spectral types. Actually Be stars do not have the same characteristics as “normal” B stars and we have to take this into account in the determination of the ratio : number of Be stars / number of B stars. We use the Bright Star Catalogue (Hoffleit & Jaschek 1982) and the Supplement to the Bright Star Catalogue (Hoffleit, Saladyga & Wlasuk 1983) containing stars V= 7.10 and brighter. This study needed to be made separately for the different spectral types because:

- Physical parameters of B stars are very different from B0 to B9;

- Emission characteristics of Be stars vary very much, with a decrease from B0e to B9e.

We successively consider three effects which can influence the frequency of Be stars:

- The over-luminosity of Be stars as compared with B stars;

- Spectral type changes during constant mass evolution;

- Spectral type changes due to the fast rotation of Be stars.

Type
6. Be Stars: Circumstellar Environment
Information
Symposium - International Astronomical Union , Volume 162: Pulsation, Rotation and Mass Loss in Early-Type Stars , 1994 , pp. 356 - 357
Copyright
Copyright © Kluwer 1994 

References

Collins, G.W. II and Sonneborn, G.H.: 1977, Astrophys. J. Suppl. Series 34, 41 Google Scholar
Hoffleit, D. and Jaschek, C.: 1982, The Bright Star Catalogue , Yale Univ. Obs.Google Scholar
Hoffleit, D., Saladyga, M. and Wlasuk, P.: 1983, A Supplement to the Bright Star Catalogue , Yale Univ. Obs.Google Scholar
Zorec, J. and Briot, D.: 1991, Astron. Astrophys. 245, 150 Google Scholar