Radial distribution of types I and II supernovae in spiral and elliptical galaxies

Abstract

From all the extragalactic supernovae registered before March 1979, 147 SN were selected in galaxies with known parameters (type, diameter, axial ratios and position angle); 114 exploded in S-galaxies (30 type I, 19 type II, and 65 undetermined) and 33 exploded in E/SO-galaxies. The surface density distribution of supernovae as a function of the relative distancef from the galactic centre was investigated. In calculating distances, we used the inclination correction, given by McCarthy (1973) for S-galaxies. The influence of selection effects (connected with bright nuclei of galaxies and with angular resolution) on the discovery of supernovae in distant galaxies has been estimated. It appears that the effects mentioned do not cause serious distortion in the radial distribution of supernovae, except in the central region of galaxies atf≤0.1. Type I supernovae (SNI) in S-galaxies are concentrated at the centre with a slight increase of density gradient and, on average, the SNI in S-galaxies and the SNI in E/SO-galaxies have similar distributions. The SNII distribution in S-galaxies exhibits a ring structure with a maximum atf=0.3–0.4. The radial distribution of SNI in S- and E-galaxies supports the view that the fractions of SNI that are formed at the white-dwarf stage (by accretion in binary systems or instability of a hot white dwarf) are not very large.