EVOLVING TO TYPE Ia SUPERNOVAE WITH SHORT DELAY TIMES

The single-degenerate model is currently a favorable progenitor model for Type Ia supernovae (SNe Ia). Recent investigations on the white dwarf (WD) + He star channel of the single-degenerate model imply that this channel is noteworthy for producing SNe Ia. In this paper, we studied SN Ia birthrates and delay times of this channel via a detailed binary population synthesis approach. We found that the Galactic SN Ia birthrate from the WD + He star channel is ∼0.3 x 10-3 yr-1 according to our standard model, and that this channel can explain SNe Ia with short delay times (∼4.5 x 107-1.4 x 108 yr). Meanwhile, these WD + He star systems may be related to the young supersoft X-ray sources prior to SN Ia explosions.