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تسجيل مستخدم جديدFinal Evolution and Delayed Explosions of Spinning White Dwarfs in Single Degenerate Models for Type Ia Supernovae
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تأليف
Omar G. Benvenuto
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We study the occurrence of delayed SNe~Ia in the single degenerate (SD) scenario. We assume that a massive carbon-oxygen (CO) white dwarf (WD) accretes matter coming from a companion star, making it to spin at the critical rate. We assume uniform rotation due to magnetic field coupling. The carbon ignition mass for non-rotating WDs is M_{ig}^{NR} approx 1.38 M_{odot}; while for the case of uniformly rotating WDs it is a few percent larger (M_{ig}^{R} approx 1.43 M_{odot}). When accretion rate decreases, the WD begins to lose angular momentum, shrinks, and spins up; however, it does not overflow its critical rotation rate, avoiding mass shedding. Thus, angular momentum losses can lead the CO WD interior to compression and carbon ignition, which would induce an SN~Ia. The delay, largely due to the angular momentum losses timescale, may be large enough to allow the companion star to evolve to a He WD, becoming undetectable at the moment of explosion. This scenario supports the occurrence of delayed SNe~Ia if the final CO WD mass is 1.38 M_{odot} < M < 1.43 M_{odot}. We also find that if the delay is longer than ~3 Gyr, the WD would become too cold to explode, rather undergoing collapse.
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