Rotational Modulation in Be Stars
The broad peaks in the periodograms of the light variations of Be stars do not resolve into individual frequencies even in a long time series. Recent CoRoT observations, in particular, clearly demonstrate their stochastic nature. These peaks, which have frequencies indistinguishable from the rotational frequency and its first harmonic, have generally been attributed to l = 2 nonradial pulsation (NRP). Stochastic variation with the rotational period is an inevitable consequence of localized mass loss for any mass-loss mechanism, including NRP. It is evident that the broad peaks are just a result of co-rotating circumstellar gas clouds. A simple model in which the mass loss is a result of magnetic flaring explains all major characteristics of Be stars.