Massive Star-Formation Regions in the Magellanic Clouds

Abstract

We present optical and UV spectroscopy of stars from six compact, luminous groups or clusters in the SMC and LMC. The groups are characterized by high concentrations of nebulosity or starlight confined to areas smaller than 30" on a side, in which some stars can be resolved. The spectra and fluxes are used to derive luminosities and effective temperatures for the stars. Spectroscopic and stellar wind properties are also noted. We find that the stars are all of O and B-type, with low extinction. The stars generally have little or no sign of stellar winds, and often have spectral peculiarities, such as weak lines or mixed spectral indicators. Most spectra have strong, broad Lyα absorption, and some have broad Ca II absorption. We place the stars on the H-R diagram, and argue that some of them are massive stars in pre-main-sequence stages of their evolution.