SCYON Abstract

Received on September 26 2006

A study of the B and Be star population in the field of the LMC open cluster NGC2004 with VLT-FLAMES

AuthorsC. Martayan (1), A.M. Hubert (1), M. Floquet (1), J. Fabregat (2), Y. Frémat (3), C. Neiner (4,1), P. Stee (5), and J. Zorec (6)
Affiliation
(1) GEPI, UMR8111 du CNRS, Observatoire de Paris-Meudon, 92195 Meudon Cedex, France
(2) Universidad de Valencía, Instituto de Ciencia de los Materiales, P.O. Box 22085, 46071 Valencía, Spain
(3) Observatoire Royal de Belgique, 3 rue Circulaire, 1180 Bruxelles, Belgium
(4) Instituut voor Sterrenkunde, KU Leuven, Celestijnenlaan 220B, 3001 Belgium
(5) Observatoire de la Côte d'Azur, avenue Nicolas Copernic, 06130 Grasse, France
(6) Institut d'Astrophysique de Paris (IAP), 98bis boulevard Arago, 75014 Paris, France
To appear inAstronomy & Astrophysics 445, 931-937 (2006)
Contactchristophe.martayan@obspm.fr
URLhttp://www.arxiv.org/abs/astro-ph/0601240
Links

Abstract

Observations of hot stars belonging to the young cluster LMC-NGC2004 and its surrounding region have been obtained with the VLT-GIRAFFE facilities in MEDUSA mode. 25 Be stars were discovered; the proportion of Be stars compared to B-type stars is found to be of the same order in the LMC and in the Galaxy fields. 23 hot stars were discovered as spectroscopic binaries (SB1 and SB2), 5 of these are found to be eclipsing systems from the MACHO database, with periods of a few days. About 75% of the spectra in our sample are polluted by hydrogen (Hα and Hγ), [SII] and [NII] nebular lines. These lines are typical of HII regions. They could be associated with patchy nebulosities with a bi-modal distribution in radial velocity, with higher values (+335 km s-1) preferentially seen inside the southern part of the known bubble LMC4 observed in HI at 21 cm.