Association of supernovae with recent star formation regions in late type galaxies

Abstract

A statistical study has been carried out to constrain the various models for the progenitors of supernovae of types Ia, Ib/c, and II. Star formation regions in late type galaxies are traced out by H II regions, imaged through photographic and CCD observations, and possible supernova association with these regions is based on the ratio of the angular separation of each supernova from its nearest H II region to the angular extent of the H II region in the direction of the supernova. The specific problems of supernova classification and positional uncertainties, as well as the probability of chance superposition, are also considered. The results suggest that type Ia supernovae do not arise from massive, short- lived stellar populations. Type Ib/c and type II supernovae, however, are very likely to be associated with H II regions and therefore with massive stellar progenitors. The single Wolf-Rayet star progenitor model for the type Ib/c supernovae is not supported. It is not clear from the results whether a difference between the association of type Ib/c supernovae and the association of type II supernovae with H II regions exists, but this probably results from the effects of small-number statistics for the type Ib/c supernovae. Not all type Ib/c and type II supernovae were found to be associated with detected H II regions; these supernovae either may have had runaway O star progenitors or were associated with H II regions below detectability.