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Astron. Astrophys. 334, 558-570 (1998)

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9. A methodological remark

Waelkens & Rufener (1985) and Waelkens (1991) reported discoveries of multiperiodic light variations of some apparently non-emission B stars, with periods in the range from 0 [FORMULA] 8 to 4 [FORMULA] 4. They called them "slowly pulsating B stars or SPB" to distinguish them from [FORMULA] Cep variables with much shorter periods ([FORMULA] 0 [FORMULA] 1 - 0 [FORMULA] 25). By its period, [FORMULA]  CMa would also qualify into this category. Clearly, one of the results of this paper represents a methodological warning that the detection of an apparent multiperiodicity with several rather close periods, typical not only for the SPB stars but also for the [FORMULA]  Cep stars and some other Be stars (cf., e.g., µ Cen: Rivinius et al. 1998) should also be tested against the hypothesis of a single and slowly periodically variable period. This is even more desirable after the finding that a number of the [FORMULA]  Cep and SPB stars are members of binary or multiple systems of stars (cf., e.g., Pigulski & Boratyn 1992, Aerts et al. 1998) since for such stars the slow periodic variations of the principal period of oscillation due to the light-time effect do inevitably occur. More generally, one should realize that many Fourier terms would be needed for a complete description of the very complicated signal which one observes in situations like this one.

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© European Southern Observatory (ESO) 1998

Online publication: May 15, 1998