The integrated spectra of M32 and of 47 Tucanae: a comparative study in the mid-ultraviolet with IUE.
ROSE J.A. and DENG S.
Abstract (from CDS):
Low-resolution mid-UV spectra of M32 and 47 Tuc have been extracted from the IUE archival database, along with spectra of 41 F and G dwarfs with well-determined atmospheric parameters and integrated spectra of 24 Galactic globular clusters. We have used five mid-UV spectral indices defined by Fanelli et al. to constrain the stellar content of M32 and 47 Tuc and to make a comparative study between the two stellar systems. In the case of 47 Tuc, the bulk of the mid-UV light is shown to come from the main-sequence turnoff stars, with much smaller (but significant) contributions coming from red horizontal-branch stars, red giants, and A stars (presumably, blue stragglers). In contrast, M32 is shown to have no significant contribution from a red horizontal-branch population, has a more metal-rich main-sequence turnoff, and has a significantly larger hot star contribution than is inferred to be present in 47 Tuc. These inferences are consistent with conclusions obtained from integrated light studies of M32 and 47 Tuc in the blue.