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arXiv 1406.4128astro-ph.HEastro-ph.SR
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单次简并吸积诱发坍塌的特征

The Signature of Single-Degenerate Accretion Induced Collapse

Anthony L. Piro, Todd A. Thompson

摘要:

吸积诱导白矮星坍缩(AIC)是恒星演化的一个自然的理论结果,但至今还没有直接观测到这一过程。这并不奇怪,因为合成的少量放射性镍($\sim10^{-3}\,M_\odot$)意味着相对暗淡的光学瞬态。在这里,我们认为,对于从一颗在成为红巨星时经历罗氏瓣溢出的恒星吸积的氧-氖-镁(ONeMg)白矮星,会出现特别强烈的AIC特征。在这种情况下,来自AIC的$\sim10^{50}\,{\rm erg}$爆炸与扩展的伴星碰撞并冲击加热其表面,产生持续$\sim1\,{\rm hr}$的X射线闪光,随后产生绝对星等为$\sim -16$到$-18$的光学特征,并持续几天到一周。这些事件在古老的恒星环境中尤其引人注目,在那里通常不会出现富含氢的超新星般的瞬变。虽然这种事件的发生率目前尚不清楚,我们描述的观察策略,可以利用高节奏的调查,应该要么检测这些事件或放置强有力的限制,他们的利率。

英文摘要:

The accretion induced collapse (AIC) of a white dwarf to a neutron star has long been suggested as a natural theoretical outcome in stellar evolution, but there has never been a direct detection of such an event. This is not surprising since the small amount of radioactive nickel synthesized ($\sim10^{-3}\,M_\odot$) implies a relatively dim optical transient. Here we argue that a particularly strong signature of an AIC would occur for an oxygen-neon-magnesium (ONeMg) white dwarf accreting from a star that is experiencing Roche-lobe overflow as it becomes a red giant. In such cases, the $\sim10^{50}\,{\rm erg}$ explosion from the AIC collides with and shock-heats the surface of the extended companion, creating an X-ray flash lasting $\sim1\,{\rm hr}$ followed by an optical signature that peaks at an absolute magnitude of $\sim -16$ to $-18$ and lasts for a few days to a week. These events would be especially striking in old stellar environments where hydrogen-rich supernova-like, transients would not normally be expected. Although the rate of such events is not currently known, we describe observing strategies that could be utilized with high cadence surveys that should either detect these events or place strong constraints on their rates.

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