Accreting CO material onto ONe white dwarfs towards accretion-induced collapse

TL;DR

This study uses stellar evolution simulations to investigate whether accreting ONe white dwarfs can undergo collapse or explosion, concluding that they are more likely to experience electron-capture collapse rather than thermonuclear explosions.

Contribution

The paper demonstrates through detailed simulations that accreting ONe white dwarfs tend to undergo collapse due to electron captures, not explosions, clarifying their final evolutionary outcomes.

Findings

Central temperature remains below explosive oxygen ignition threshold.

Different initial masses and accretion rates influence density and temperature evolution.

Collapse is driven by electron captures, not thermonuclear explosions.

Abstract

The final outcomes of accreting ONe white dwarfs (ONe WDs) have been studied for several decades, but there are still some issues not resolved. Recently, some studies suggested that the deflagration of oxygen would occur for accreting ONe WDs with Chandrasekhar masses. In this paper, we aim to investigate whether ONe WDs can experience accretion-induced collapse (AIC) or explosions when their masses approach 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 WDs undergo weak multicycle carbon flashes during the mass-accretion process, leading to the mass increase of the WDs. We found that different initial WD masses and mass-accretion rates have influence on the evolution of central density and temperature. However, the central temperature cannot reach the explosive oxygen ignition temperature due to the neutrino cooling. This work implies that the final outcome of accreting ONe WDs is electron-capture induced collapse rather than thermonuclear explosion.