Sternberg State Astronomical Institute, Moscow, U.S.S.R.
(Received 26 November, 1985)
Abstract. Revised photometric data are used to compare the light and colour curves of type I and type II supernovae (SNe I, SNe II); their statistical properties are also compared. No significant difference between SNe I and SNe II has been found in their radial distribution and frequency of outbursts in spiral galaxies. The comparison of light and colour curves reveals several features common to both types and the possibility of transition between types.
The Sternberg Astronomical Institute Supernova Catalogue was compiled and is regularly updated. The latest version contains data on 930 supernovae (SNe). We also compiled the photometric catalogue of supernovae. Together with the database of Sternberg Institute Supernova search and the plate collection they form the base for our statistical studies of SNe, with major attention on SN frequency, spatial distribution of SNe in the galaxies, distributions of absolute magnitudes and other photometric characteristics of SNe. We present the following recent results. The surface density of SNe decreases with distance from galaxy centers similar to the surface brightness, but distribution of SNe is continuing beyond the optical radius of galaxies, with abrupt change of slope. The radial distribution of type Ia SNe in spiral galaxies is only slightly steeper than the one for SNe II, while SNe Ib/c are more concentrated towards the central regions. SNe Ia in spiral galaxies reveal significant concentration to the spiral arms, similar to the one observed for SNe II and SNe Ib/c. SNe of types Ib/c and II show a strong concentration towards H II regions, while distribution of SNe Ia can be explained by chance superposition. So the progenitors of SNe Ia in spiral galaxies are likely the stars with initial masses range near 4 -- 8 M$\odot$. We present the composite light curve for type Ia SNe based on the data of our catalogues, indicating large scatter of SNe Ia absolute magnitudes.