The WD+He star binaries as the progenitors of type Ia supernovae

• Main Authors: Wang Bo, Liu Dongdong
• Format: Article
• Language: English
• Published: De Gruyter 2017-12-01
• Series: Open Astronomy
• Subjects: white dwarfs; binaries-close; stars-evolution
• Online Access: https://doi.org/10.1515/astro-2017-0018

Employing the MESA stellar evolution code, we computed He accretion onto carbon-oxygen white dwarfs (CO WDs).We found two possible outcomes for models in which the WD steadily grows in mass towards the Chandrasekhar limit. For relatively low He-accretion rates carbon ignition occurs in the center, leading to a type Ia supernova (SN Ia) explosion, whereas for relatively high accretion rates carbon is ignited off-center, probably leading to collapse. Thus the parameter space producing SNe Ia is reduced compared to what was assumed in earlier papers, in which the possibility of off-center ignition was ignored. We then applied these results in binary population synthesis modelling, finding a modest reduction in the expected birthrate of SNe Ia resulting from the WD+He star channel.