Effects of a new triple-$\alpha$ reaction rate on the helium ignition of accreting white dwarfs

TL;DR

This study investigates how a new triple-alpha reaction rate influences helium ignition in accreting white dwarfs, affecting the conditions leading to Type Ia supernovae explosions across various accretion rates.

Contribution

It introduces a revised triple-alpha reaction rate and explores its impact on ignition conditions in white dwarfs, revealing new ignition regimes and thresholds for supernova initiation.

Findings

Nuclear burnings ignite at helium layers for all accretion rates studied.

Lower accretion rates can trigger carbon deflagration, previously thought to require higher rates.

Off-center helium detonation occurs at intermediate and slow accretion rates.

Abstract

Effects of a new triple-alpha reaction rate on the ignition of carbon-oxygen white dwarfs accreting helium in a binary systems have been investigated. The ignition points determine the properties of a thermonuclear explosion of a Type Ia supernova. We examine the cases of different accretion rates of helium and different initial masses of the white dwarf, which was studied in detail by Nomoto. We find 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 compared to that of $dM/dt\simeq 4\times10^{-8} M_{\odot} \rm yr^{-1}$ which has been believed to the lower limit of the accretion rate for the deflagration supernova. Furthermore, off-center helium detonation should result for intermediate and slow accretion rates and the region of carbon deflagration for slow accretion rate is disappeared.