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Paper: Statistical Inference of the Be Star Periodicity (Invited Review)
Volume: 361, Active OB-Stars: Laboratories For Stellar and Circumstellar Physics
Page: 27
Authors: Hubert, A.M.
Abstract: A review of periodicities with different timescales found in photometric and line profile variability of Be stars from visual, UV, and X-ray observations is presented. A distinction is made between what are called “stable” periods, “transient” periods and cyclic variations. Firstly, the report focuses on the intrinsic variability of Be stars. I attempt to distinguish between variations due to non-radial pulsations and those due to corotating magnetic structures at or near the stellar surface. As the rotational period is a critical value for selection of processes giving rise to short-term periodicities, estimates provided by rotational modulation attributes are compared with those derived from fundamental parameters. Then, I give an overview of new spatial instrumentation, which will improve our understanding of the origin and nature of Be stars through analyses of their light curves. Secondly, periodicities with longer time scales are considered. These periods are associated with binary systems. Though binarity is irrelevant to the Be phenomenon in many cases, it cannot be excluded that a significant number of Be stars are formed through binary processes. Thus, periodicities linked to mass transfer or orbital effects are analyzed in an evolutionary scheme. Thirdly, long-term cyclic variations that reflect the dynamical state of Be star disks are briefly reviewed.
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