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C. Martayan, J. Zorec, D. Baade, Y. Frémat, J. Fabregat & S. Ekström

Evolution of massive Be and Oe stars at low metallicity towards the Long Gamma Ray bursts

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Abstract

Several studies have shown recently that at low metallicity B-type stars rotate faster than in environments of high metallicity. This is a typical case in the SMC. As a consequence, it is expected that a larger number of fast rotators is found in the SMC than in the Galaxy, in particular a higher fraction of Be/Oe stars. Using the ESO-WFI in its slitless mode, the data from the SMC open clusters were examined and an occurrence of Be stars 3 to 5 times larger than in the Galaxy was found. The evolution of the angular rotational velocity at different metallicities seems to be the main key to understand the specific behavior and evolution of these stars. According to the results from the WFI study, the observational clues drawn from theWR stars and other massive stars in the SMC, and relying on the model predictions regarding the characteristics that LGRBs-progenitors should have on the ZAMS, we concluded that low metallicity Oe/Be stars are potential progenitors of LGRBs. In this document, we describe the different steps followed in these studies: determination of the number of Be/Oe stars at different metallicities, identification of the clues that lead to suppose the low metallicity Be/Oe stars as LGRB progenitors, comparison of models with observations.

To cite this article

C. Martayan, J. Zorec, D. Baade, Y. Frémat, J. Fabregat & S. Ekström, «Evolution of massive Be and Oe stars at low metallicity towards the Long Gamma Ray bursts», Bulletin de la Société Royale des Sciences de Liège [En ligne], Volume 80 - Année 2011, 285 - 290 URL : https://popups.uliege.be/0037-9565/index.php?id=2750.

About: C. Martayan

ESO, Alonso de Cordova 3107 Vitacura, Santiago, Chile, and GEPI, Observatoire de Paris, place Jules Janssen 92195 Meudon Cedex, France

About: J. Zorec

Institut d’Astrophysique de Paris, UMR7095 CNRS, Université P & MC, 98bis boulevard Arago, 75014 Paris, France

About: D. Baade

ESO, Karl-Schwarschild-Str. 2, Garching bei Muenchen, Germany

About: Y. Frémat

Royal Observatory of Belgium, 3 avenue circulaire, 1180 Brussels, Belgium

About: J. Fabregat

Observatorio Astronomico de Valencia, 46980 Paterna Valencia, Spain

About: S. Ekström

Geneva Observatory, University of Geneva, Maillettes 51, 1290 Sauverny, Switzerland