DISTRIBUTION OF SUPERNOVAE RELATIVE TO SPIRAL ARMS AND H-II-REGIONS

We have studied the association of supernovae in spiral galaxies with sites of recent star formation-spiral arms and H II regions. It is sho wn that supernovae (SNe) of Types Ia, Ib, and II exhibit concentration to spiral arms and their distributions over the distance to the neare st spiral arm do not differ significantly. This result is confirmed by a Kolmogorov-Smimov test comparison with the distance distributions, expected if SNe are distributed randomly inside the model galaxy. SNe of Types Ib and II show a strong concentration towards H II regions, w hile distribution of SNe Ia can be explained by chance superposition. All studied distributions of SNe Ib and II show striking similarity, w hich suggests that their progenitors are massive stars with similar ag es and initial masses. The association of SNe Ia with spiral arms sugg ests that their progenitors in spiral galaxies are likely to be interm ediate mass stars.