2021/03/10 by Ruediger Pakmor, Yossef Zenati, Hagai B. Perets +1 · 1 citation
Physics and Astronomy · #astro-ph.SR
paper · pdf · doi:10.1093/mnras/stab686
14 pages, 10 figures, accepted by MNRAS, comments welcome
arxiv created 2021/03/10 · arxiv updated 2021/03/17
Normal type Ia supernovae (SNe) are thought to arise from the thermonuclear explosion of massive (>0.8 M_\odot) carbon-oxygen white dwarfs (WDs), although the exact mechanism is debated. In some models helium accretion onto a carbon-oxygen (CO) WD from a companion was suggested to dynamically trigger a detonation of the accreted helium shell. The helium detonation then produces a shock that after converging on itself close to the core of the CO-WD, triggers a secondary carbon detonation and gives rise to an energetic explosion. However, most studies of such scenarios have been done in one or two dimensions, and/or did not consider self-consistent models for the accretion and the He-donor. Here we make use of detailed 3D simulation to study the interaction of a He-rich hybrid 0.69 M_\odot HeCO WD with a more massive 0.8 M_\odot CO~WD. We find that accretion from the hybrid WD onto the CO~WD gives rise to a helium detonation. However, the helium detonation does not trigger a carbon detonation in the CO~WD. Instead, the helium detonation burns through the accretion stream to also burn the helium shell of the donor hybrid HeCO-WD. The detonation of its massive helium shell then compresses its CO core, and triggers its detonation and full destruction. The explosion gives rise to a faint, likely highly reddened transient, potentially observable by the Vera Rubin survey, and the high-velocity (∼ 1000 \mathrmkm s-1) ejection of the heated surviving CO~WD companion. Pending on uncertainties in stellar evolution we estimate the rate of such transient to be up to ∼10% of the rate of type Ia SNe.