YOUNG AND MASSIVE BINARY PROGENITORS OF TYPE Ia SUPERNOVAE AND THEIR CIRCUMSTELLAR MATTER

We present new evolutionary models for Type Ia supernova (SN Ia) progenitors, where we include massstripping effect on a main-sequence (MS) or slightly evolved companion star by winds from a mass-accreting white dwarf (WD). The mass-stripping attenuates the rate of mass transfer from the companion to the WD. As a result, quite a massive MS companion can avoid forming a common envelope to increase the WD mass up to the SN Ia explosion. Properly formulating the mass-stripping effect, we follow binary evolutions of the WD + MS systems and obtained a parameter region where SNe Ia are resulted in the initial donor mass – binary orbital period plane. The newly obtained SN Ia region extends to the donor mass up to 6 − 7 M⊙, although its extension depends on the efficiency of mass-stripping effect. The stripped matter would mainly be distributed on the orbital plane and form very massive circumbinary matter around the SN Ia progenitor. It can explain the circumstellar matter around SNe Ia/IIn(IIa) 2002ic and 2006gj as well as normal SN Ia 2006X. Our new model suggests the presence of very young (. 108 yr) populations of SN Ia progenitors, being consistent with recent observational indications of young population SNe Ia. Subject headings: binaries: close — circumstellar matter — stars: winds, outflows — supernovae: individual (SN2002ic, SN 2005gj, SN 2006X)