Distribution of supernovae relative to spiral arms and H II regions

Abstract

We have studied the association of supernovae in spiral galaxies with sites of recent star formation--spiral arms and H II regions. It is shown that supernovae (SNe) of Types Ia, Ib and II exhibit concentration to spiral arms and their distributions over the distance to the nearest spiral arm to not differ significantly. This result is confirmed by a Kolmogorov-Smirnov 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, while distribution of SNe Ia can be explained by chance superposition. All studied distributions of SNe Ib and II show striking similarity, which suggests that their progenitors are massive stars with similar ages and initial masses. The association of SNe Ia with spiral arms suggests that their progenitors in spiral galaxies are likely to be intermediate mass stars.