Effects of a New Triple-α Reaction Rate on the Helium Ignition of Accreting White Dwarfs

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Effects of a new rate of the triple-α reaction on the ignition of a carbon-oxygen white dwarf accreting helium in a binary system have been investigated. The ignition points determine the properties of a thermonuclear explosion of a Type Ia supernova (SNIa). We examine the evolutionary tracks of white dwarfs with various accretion rates and initial masses. It is found that for all cases from slow to intermediate accretion rates, nuclear burnings are ignited at the helium layers. As a consequence, carbon deflagration would be triggered for the lower accretion rate than dM/dt≈4x10^-8 M_sun yr^-1 which has been believed to the lower limit of the accretion rate for the deflagration supernova. Furthermore, the off-center helium detonation dominates the mechanism of SNIa for intermediate and slow accretion rates.