Worlf-Rayet Stars in the Large Magellanic Cloud

Abstract

Photometric data in blue (B), visual (V), and red (R) light are presented for 58 Wolf–Rayet stars in the Large Magellanic Cloud, together with finding charts for 53 of the objects. The WC stars are found to have a consistently smaller V–R colour than the WN stars. This is used to classify stars for which a spectroscopic class is not available. The luminosity of the WN stars is dependent on their location: the most luminous are found in the 30 Doradus complex; they are about two magnitudes brighter than the field WN stars. An evolutionary interpretation of the observed surface and magnitude distribution is proposed. The Wolf–Rayet stars are among the stars formed with masses near the limit for stability. They exhaust most of their hydrogen and reach the turn-off point thoroughly mixed. From then on they evolve by mass loss, the rate of which is not necessarily greater than a few solar masses per 10 ⁶ years. It is suggested that field Wolf–Rayet stars as well as other luminous Population I field stars exist because field stars, single and multiple, form as well as associations in huge proto-clouds with dimensions up to 1000 pc.