Supernovae and Massive Star Formation Regions

We have extended the work of Van Dyk [AJ, 103, 1788 (1992)] on the association of supernovae with massive star formation regions, as traced by giant H II regions, in late-type galaxies. In this paper, we concentrate only on supernovae arising from massive progenitors, Type Ib/c and Type II, using ground-based CCD Hα images. We improve upon earlier studies by increasing the supernova sample, by including only spectroscopically classified supernovae, and by obtaining more accurate astrometry of the supernovae and their environments. We find that the degree of association of both supernova types with H II regions in their parent galaxies is not significantly different, implying that both types arise from essentially the same range of stellar masses. From consideration of the statistics in this paper, including the Hα luminosities of the H II regions with which supernovae are associated, we can exclude the Wolf-Rayet star progenitor model for most Type Ib/c supernovae. Instead, the progenitors of Type Ib/c supernovae are probably in relatively close binary systems, rather than single stars or stars in wide binaries (possible progenitor systems for Type Il supernovae); interaction with a companion star can severely deplete the hydrogen envelope prior to explosion.