Towards ensemble asteroseismology of the young open clusters chi Persei and NGC 6910

As a result of the variability survey in chi Persei and NGC 6910, the number of beta Cep stars that are members of these two open clusters is increased to twenty stars, nine in NGC 6910 and eleven in chi Persei. We compare pulsational properties, in particular the frequency spectra, of beta Cep stars in both clusters and explain the differences in terms of the global parameters of the clusters. We also indicate that the more complicated pattern of the variability among B-type stars in chi Persei is very likely caused by higher rotational velocities of stars in this cluster. We conclude that the sample of pulsating stars in the two open clusters constitutes a very good starting point for the ensemble asteroseismology of beta Cep-type stars and maybe also for other B-type pulsators. (C) 2010 WILEY-VCH Verlag GmbH&Co. KGaA, Weinheim