MASSIVE STAR FORMATION IN H-II GALAXIES - THE PRESENCE OF WOLF-RAYET STARS

A search for WR features in the spectra of a large sample of H II galaxies selected from the Spectroscopic Catalogue of H II Galaxies has been performed. The detection rate was found to be of 10%. Different possible observational bias were investigated but none was found to affect the results. Then the reasons for such a low detection rate have to be found among the physical properties of the considered galaxies. The influence of the metallicity was first investigated. Our main result is that no WR features were detected in galaxies with Z < 0.1 Z.. That lack of WR detection in low metallicity systems is thought to be due to the fact that massive stars never reach the WR stage in such media. What could be a consequence of the claimed dependence of the lower mass limit for WR progenitors on metallicity. Above that limit, we found that the same range of Blue Bump luminosities can be found at any metallicity. Thus, the detection of appreciable amounts of WR stars seems to be primarily governed by the evolutionary stage of the starburst. The SNeII contribution to the Blue Bump has been also analyzed. The data suggest that large blue bump luminosities have to be expected in regions with SN contamination and therefore it could be dangerous to directly translate Blue Bump luminosities into number of WR stars.