Astron. Astrophys. 345, 505-513 (1999)

7. Discussion and conclusions

The discovery of  Cephei pulsations in Oo 692 and Oo 992, the two early B-type stars located in the central region of h Persei, together with our findings described in Paper I mean, that the double cluster h and  Persei is indeed rich in these kind of variables. Since our up-to-date observations were confined to the central regions of the double cluster, more stars of this type may be discovered. Regarding the richness of h and  Persei, we estimated that the clusters should contain about 10-15  Cephei stars. Candidates have already been selected and observations of other fields in both clusters are now under way.

Another interesting discovery in h Persei is finding of SPB-type variations in Oo 893. Although the star is monoperiodic within the detection limit of our observations, the distinct wavelength dependence of the amplitude of variations is a strong argument in favour of an SPB classification. Many monoperiodic stars found in the HIPPARCOS data (Waelkens et al. 1998) were also classified as SPBs. It seems, therefore, that multiperiodicity cannot be longer regarded as a necessary condition for classifying a star as an SPB. Consequently, some of the monoperiodic variables found by Balona and co-workers in three southern young open clusters (Balona 1994; Balona & Koen 1994; Balona & Laney 1994) could be, in fact, SPB stars.

© European Southern Observatory (ESO) 1999

Online publication: April 19, 1999
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