The young Large Magellanic Cloud clusters NGC 2004 and 2100 and their short-period variables

Abstract

In this paper we present results of intensive CCD monitoring in the V-band of stars in two young LMC clusters: NGC 2004 and 2100. Each star in these clusters was observed about 10- 1 5 times per night for about 12 nights, with the aim of detecting β Cep stars in these metal-poor clusters and thereby testing the hypothesis that pulsation in these stars is driven by ionization of metals. Our results strongly support this idea, since we have failed to find any β Cep variables. The probability that the difference between the relative numbers of β Cep stars in the Galaxy and in these two clusters is due to chance is less than 0.1 per cent