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Massive Oe/Be stars at low metallicity: candidate progenitors of long GRBs?

Published online by Cambridge University Press:  12 July 2011

Christophe Martayan
Affiliation:
ESO, Chile GEPI-Observatoire de Meudon, France
Dietrich Baade
Affiliation:
ESO, Germany
Juan Zorec
Affiliation:
Instritut d'Astrophysique de Paris, France
Yves Frémat
Affiliation:
Royal Observatory of Belgium, Brussels, Belgium
Juan Fabregat
Affiliation:
Valencia University, Spain
Sylvia Ekström
Affiliation:
Geneva Observatory, Switzerland
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Abstract

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At low metallicity B-type stars rotate faster than at higher metallicity, typically in the SMC. As a consequence, a larger number of fast rotators is expected in the SMC than in the Galaxy, in particular more Be/Oe stars. With the ESO-WFI in its slitless mode, we examined the SMC open clusters and found an occurence of Be stars 3 to 5 times larger than in the Galaxy. The evolution of the angular rotational velocity seems to be the main key on the understanding of the specific behaviour and stellar evolution of such stars at different metallicities. With the results of this WFI study and using observational clues on the SMC WR stars and massive stars, as well as the theoretical indications of long gamma-ray burst progenitors, we identify the low metallicity massive Be and Oe stars as potential LGRB progenitors. Therefore the expected rates and numbers of LGRB are calculated and compared to the observed ones, leading to a good probability that low metallicity Be/Oe stars are actually LGRB progenitors.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2011

References

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