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Paper: The Evolutionary Status of Be Stars (Invited Talk)
Volume: 361, Active OB-Stars: Laboratories For Stellar and Circumstellar Physics
Page: 349
Authors: McSwain, M.V.; Gies, D.R.
Abstract: Be stars are a class of rapidly rotating B stars with circumstellar disks that cause Balmer and other line emission. To investigate the origin of their rapid rotation, we have conducted a photometric survey of 48 open clusters in the southern sky. We use our results to examine the age and evolutionary dependence of the Be phenomenon. We find an overall increase in the fraction of Be stars with age until 100 Myr, and Be stars are most common among the evolved B-type stars above the zero-age MS (ZAMS). We show that a spin-up phase at the terminal-age MS (TAMS) cannot produce the observed distribution of Be stars, but about 75% of the Be stars detected may have been spun-up by binary mass transfer. Most of the remaining Be stars were likely rapid rotators at birth.
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