ON THE PROGENITORS OF TYPE-IA SUPERNOVAE IN EARLY-TYPE AND LATE-TYPE GALAXIES

An examination of recent observational material reveals substantial differences between supernovae of Type Ia (SNs Ia) in galaxies of different Hubble types. We propose that SNs la in late- and early-type galaxies may have different progenitors. A further examination of novae in galaxies of different Hubble types suggests the possibility that SNs Ia in late-type galaxies may be related to cataclysmic variable-type systems, while SNs Ia in early-type galaxies may be related to mechanisms involving an older population. About 50%-70% of the SNs Ia events in spirals observed at the La Silla and Tololo Observatories in the past 4 years appear to be located in the arms of the parent galaxy.