000002037 001__ 2037
000002037 005__ 20160701171657.0
000002037 0247_ $$2DOI$$a10.1051/0004-6361:20053859
000002037 037__ $$aASTROimport-194
000002037 100__ $$aMartayan, C.
000002037 245__ $$aEffects of metallicity, star-formation conditions, and evolution in B and Be stars. I. Large Magellanic Cloud, field of NGC 2004
000002037 260__ $$c2006
000002037 520__ $$aAims.To statistically study the effects of the metallicity, star-formation conditions, and evolution on the behaviour of massive stars and, more particularly, of B and Be stars, we observed large samples of stars in the Magellanic Clouds for the first time. In this article we present the first part of this study. Methods: .Spectroscopic observations of hot stars belonging to the young cluster LMC-NGC 2004 and its surrounding region were carried out with the VLT-GIRAFFE facilities in MEDUSA mode. We determined the fundamental parameters (T_eff, log~g, V sin i, and radial velocity) for all B and Be stars in the sample thanks to a code developed in our group. The effect of fast rotation (stellar flattening and gravitational darkening) are taken into account in this study. We also determined the age of observed clusters. We then compared the mean V sin i obtained for field and cluster B and Be stars in the Large Magellanic Cloud (LMC) with the ones in the Milky Way (MW). Results: .We find, in particular, that Be stars rotate faster in the LMC than in the MW, in the field as well as in clusters. We discuss the relations between V sin i, metallicity, star-formation conditions, and stellar evolution by comparing the LMC with the MW. We conclude that Be stars began their main sequence life with an initial rotational velocity higher than the one for B stars. It is probable that only part of the B stars, those with a sufficient initial rotational velocity, can become Be stars. This result may explain the differences in the proportion of Be stars in clusters with similar ages. 
000002037 700__ $$a Frémat, Y.
000002037 700__ $$a Hubert, A.-M.
000002037 700__ $$a Floquet, M.
000002037 700__ $$a Zorec, J.
000002037 700__ $$a Neiner, C.
000002037 773__ $$c273-284$$i1$$pAstronomy and Astrophysics$$v452$$y2006
000002037 85642 $$ahttp://esoads.eso.org/abs/2006A%26A...452..273M
000002037 905__ $$apublished in
000002037 980__ $$aREFERD