A New Progenitor Model of Type Ia Supernovae

Abstract

A new progenitor model of Type Ia supernovae (SNe Ia) is proposed. The model consists of a carbon-oxygen white dwarf (0.8–1.2 M⊙) and a low-mass red giant star (0.8–1.5 M⊙) with a helium core (0.2–0.4 M⊙). When a red giant fills its inner critical Roche lobe and its mass transfer rate exceeds a critical value, a common envelope state is realized. Then the mass accretion rate onto the white dwarf, i.e., the mass transfer rate is tuned up to be Ṁ= 8.5 x10−7 (MWD/ M⊙−0.52) M⊙ yr−1, where MWD is the mass of the white dwarf. This rate is high enough to suppress the hydrogen shell flashes, but too low for carbon to be ignited off-center. When the carbon-oxygen core mass grows to the Chandrasekhar limit during the common envelope phase, a Type Ia supernova explosion is expected to occur.