Supernovae of type I as end products of the evolution of binaries with components of moderate initial mass.

Formation frequencies of binary systems which may become Type I supernovae are estimated. Presupernova systems consist of a CO or He degenerate dwarf and a (potential) mass donor (main-sequence star = MS; low-mass red giant = RG; asymptotic giant branch star = AGB; CO or He degenerate dwarf = CODD or HeDD). Mass transfer is driven by nuclear evolution (E), capture from wind (W), a magnetic stellar wind (MSW), or gravitational wave radiation (GWR). For several scenarios, the composition of accretor, nature of donor, driving mechanism, and formation frequency (in 10^-3 yr^-1 per 10¹⁰ L_sun; in the B band), respectively, are the following: (1) CO, RG, E, 10^-2- 10^-3; (2) CO, AGB, W, 4; (3) CO, MS, MSW, 2; (4) He, MS, MSW, 2; (5) CO or He, near-MS, E+MSW, 3; (6) CO, CODD, GWR, 8; (7) CO, HeDD, GWR, 1; (8) He, HeDD, GWR, 5. The galactic Type I supernova frequency is 10.