Pre-explosion Helium Shell Flash in Type Ia Supernovae

Abstract I study the possibility that within frame of core degenerate (CD) scenario for type Ia supernovae (SNe Ia) merger process asymptotic giant branch (AGB) star and white dwarf (WD) maintains an envelope mass ≈0.03 M ⊙ causes a later helium shell flash. estimate number pre-explosion flash events to be less than few per cent all CD SNe Ia. A while moves left on HR diagram as post-AGB (late thermal pulse—LTP) or along WD cooling track (very LTP—VLTP) expand become “born again” AGB star. Merger remnants exploding still form hydrogen-polluted peculiar Ia, explosion inside inflated born-again results in early flux excess light curve SN The fraction systems might show due LTP/VLTP is <few × 10 −4 much below observed fraction. In with result from ejecta collision planetary nebula fallback gas, mixing 56 Ni outer regions ejecta. Ongoing sky surveys find about one case year where influences curve.