Star formation and extinction in extragalactic H II regions.

Abstract

Evolutionary models are presented of far UV luminosity, production of ionizing photons, effective temperature, and ejection of heavy elements for an ionizing star cluster. The way in which interstellar extinction in our Galaxy and inside and outside the H II region affects the UV and optical emission of the complex is discussed. Conclusions are derived from a comparison of the results with observational data. It is found that long-duration continuous star formation in these objects is excluded. Star formation in extragalactic H II regions proceeds in very short bursts, at least for massive stars which are the only ones for which information is available.