engleski

Omega Orionis and the Be stars

We summarize the results of a multisite spectroscopic and photometric campaign on the Be star omega Orionis. There is only one period, P = 0.97d, which is visible in the photometry and line profile variations. We caution against the indiscriminate use of the radial velocity to infer multiperiodicity. The helium lines are narrower than the metal lines and may be contaminated by circumstellar material. The line profiles show two excess absorption features moving in antiphase. As in other Be stars, the periodic variations are clearly present in the emission wings of some helium lines and in the core of Hbeta. From this we conclude that the periodic variations are most probably associated with co-rotating circumstellar material. We discuss the Be stars in terms of a fast magnetic rotator model.

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