期刊
ASTROPHYSICAL JOURNAL
卷 771, 期 1, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.1088/0004-637X/771/1/14
关键词
novae, cataclysmic variables; nuclear reactions, nucleosynthesis, abundances; supernovae: general; white dwarfs
资金
- David and Lucile Packard Foundation
- NSF [AST-0847563]
- NASA Earth and Space Science Fellowship
- DGAPA-PAPIIT-UNAM [IA101413-2]
- Direct For Mathematical & Physical Scien [0847563] Funding Source: National Science Foundation
- Division Of Astronomical Sciences [0847563] Funding Source: National Science Foundation
Several models for Type Ia-like supernova events rely on the production of a self-sustained detonation powered by nuclear reactions. In the absence of hydrogen, the fuel that powers these detonations typically consists of either pure helium (He) or a mixture of carbon and oxygen (C/O). Studies that systematically determine the conditions required to initiate detonations in C/O material exist, but until now no analogous investigation of He matter has been conducted. We perform one-dimensional reactive hydrodynamical simulations at a variety of initial density and temperature combinations and find critical length scales for the initiation of He detonations that range between 1 and 10(10) cm. A simple estimate of the length scales over which the total consumption of fuel will occur for steady-state detonations is provided by the Chapman-Jouguet (CJ) formalism. Our initiation lengths are consistently smaller than the corresponding CJ length scales by a factor of similar to 100, providing opportunities for thermonuclear explosions in a wider range of low-mass white dwarfs (WDs) than previously thought possible. We find that virialized WDs with as little mass as 0.24 M-circle dot can be detonated, and that even less massive WDs can be detonated if a sizable fraction of their mass is raised to a higher adiabat. That the initiation length is exceeded by the CJ length implies that certain systems may not reach nuclear statistical equilibrium within the time it takes a detonation to traverse the object. In support of this hypothesis, we demonstrate that incomplete burning will occur in the majority of He WD detonations and that Ca-40, Ti-44, or Cr-48, rather than Ni-56, is the predominant burning product for many of these events. We anticipate that a measure of the quantity of the intermediate-mass elements and Ni-56 produced in a helium-rich thermonuclear explosion can potentially be used to constrain the nature of the progenitor system.
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