WOLF-RAYET GALAXIES - AN INTRODUCTION AND A CATALOG

The first catalog of Wolf-Rayet galaxies is presented and discussed. These are a subset of emission-line galaxies in which a broad 4686 He II emission feature due to Wolf-Rayet (W-R) stars is observed in the integrated spectrum. About one-quarter of these galaxies also show a broad line at 4640 angstrom due to N III which is prominent in the latest type WN stars. The number of Lyman-continuum photons emitted by W-R galaxies scales roughly with their integrated magnitudes, similar to emission-line galaxies. Both W-R galaxies and emission-line galaxies form an overlap with and luminous extension of giant H II regions in these properties. The fraction of W-R stars to O stars in some of these galaxies appears to be large, which if confirmed by more detailed quantitative work would imply that the initial mass function was relatively "flat." There is also another small subset of emission-line galaxies in which a narrow 4686 He II emission feature is found-this is likely a recombination nebular line whose excitation mechanism is uncertain.