Accreting material onto ONe white dwarfs towards accretion-induced collapse [SSA]

The final outcomes of an accreting ONe white dwarf (ONe WD) have been studied for several decades, but there are still some important issues not resolved. Recently, several studies suggested that the deflagration of oxygen would occur for an accreting ONe WD with Chandrasekhar mass. In this paper, we aim to investigate whether the ONe WD can experience accretioninduced collapse (AIC) or explosion when its mass approaches the Chandrasekhar limit. Employing the stellar evolution code modules for experiments in stellar astrophysics (MESA), we simulate the long-term evolution of ONe WDs by accreting CO material. The ONe WD undergoes weak multicycle carbon flashes during the mass-accretion process, leading to the mass increase of the WD. We found that the WD can be heated up due to the electroncapture reactions, but the central temperature cannot reach the explosive oxygen ignition temperature because of the neutrino cooling even if in the conditions of different mass-accretion rates. Our results imply that the final outcome of accreting ONe WDs is electron-capture induced collapse rather than thermonuclear explosion.

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C. Wu and B. Wang
Fri, 13 Oct 17

Comments: 10 pages, 7 figures, submitted to MNRAS