UBV stellar photometry of bright stars in GC M5. II. Physical parameters of HB stars

Abstract

The physical parameters of the stars in the central region of the globular cluster M5 (NGC 5904) were determined from UBV photometry using Kurucz (1992) synthetic flux distributions and some empirical relations. It is found that the bluest horizontal branch stars have higher luminosities than predicted by canonical zero-age horizontal branch models. Parameters of the mass distribution on the HB stars are determined. It is shown that the gap in the blue HB previously reported (Markov et al. 1999) is probably a statistical fluctuation.