Distribution of Supernovae in Spiral Galaxies

Data are presently available on 156 supernovae (SNe) of known type that have occurred in spirals of types Sa-Sc having inclinations i < 70 degrees. The surface density distribution of SN Ibc + SN II is found to be an exponential with exponent -4.5 r(SN) / R(25) . Available data suggest, but do not yet prove, that SNe Ibc may be more centrally concentrated than SNe II. It is tentatively suggested that such an effect might be due to preferential mass loss via stellar winds, in the relatively metal-rich progenitors of core-collapse supernovae (or by an enhanced mass transfer rate in binary SN progenitors) in the high metallicity central regions of spiral galaxies.