Beta Cephei and SPB stars in the Large Magellanic Cloud

Abstract

This is a progress report of the study of pulsating main-sequence stars in the LMC. Using the OGLE-II photometry supplemented by the MACHO photometry, we find 64 Beta Cephei stars in the LMC. Their periods are generally much longer than observed in stars of this type in the Galaxy (the median value is 0.27 d compared with 0.17 d in the Galaxy). In 20 stars with short periods attributable to the Beta Cephei-type instability, we also find modes with periods longer than 0.4 d. They are likely low-order g modes, which means that in these stars both kinds of variability, Beta Cephei and SPB, are observed. We also show examples of the multiperiodic SPB stars in the LMC, the first beyond our Galaxy.

4 pages, 3 figures; to appear in the proceedings of the IAU Colloquium 193 `Variable Stars in the Local Group', eds. Don Kurtz and Karen Pollard