Analysis of the optical spectra of Wolf-Rayet galaxies

Extract

Wolf-Rayet (W-R) galaxies are a subset of emission-line galaxies in whose integrated spectra a broad (i.e., stellar in origin) He II λ 4686 emission feature has been detected. This line is a prominent emission feature in the spectra of WN stars. The presence of 10² to 10⁵ W-R stars in these galaxies has been inferred from a comparison of the luminosity and equivalent width of this feature in the integrated galaxy spectra with those of the corresponding line in the spectra of Galactic and LMC WN stars. Most W-R galaxies exhibit other properties indicative of a very young starburst population, such as a relatively “blue” continuum and a strong nebular emission line spectrum due to photoionization by large numbers of hot, early-type stars. Their spectra are therefore very similar to to those of giant H II regions. There are currently about 40 W-R galaxies known.