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arXiv 1109.4652astro-ph.SR
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Ia型超新星的核心简并方案

The core-degenerate scenario for type Ia supernovae

Noam Soker

摘要:

在Ia型超新星(SNe)形成的核心简并(CD)假设中,质量为1000万的白矮星(WD)是由WD伴星与一颗大质量渐近巨星分支(AGB)恒星的热核心合并而形成的。WD被破坏并堆积在更大的核心上。在CD方案中,快速旋转的WD形成于恒星形成幕之后不久,恒星形成到爆炸的延迟时间基本上取决于快速旋转的合并残余物的自旋下降时间。自旋下降是由于磁偶极子辐射力矩。与双简并(DD)方案相比,CD方案的几个性质使其具有吸引力。(1)合并过程中不太可能发生碳的偏离中心点燃。(2)没有形成大的信封。因此,避免了过多的质量损失,这可能会使合并残余物低于临界质量。(3)这个模型解释了更明亮的Ia超新星优先出现在恒星形成星系中的发现。

英文摘要:

In the core-degenerate (CD) scenario for the formation of Type Ia supernovae (SNe) the Chandrasekhar or super-Chandrasekhar mass white dwarf (WD) is formed at the termination of the common envelope phase or during the planetary nebula phase, from a merger of a WD companion with the hot core of a massive asymptotic giant branch (AGB) star. The WD is destructed and accreted onto the more massive core. In the CD scenario the rapidly rotating WD is formed shortly after the stellar formation episode, and the delay from stellar formation to explosion is basically determined by the spin-down time of the rapidly rotating merger remnant. The spin-down is due to the magneto-dipole radiation torque. Several properties of the CD scenario make it attractive compared with the double-degenerate (DD) scenario. (1) Off-center ignition of carbon during the merger process is not likely to occur. (2) No large envelope is formed. Hence avoiding too much mass loss that might bring the merger remnant below the critical mass. (3) This model explains the finding that more luminous SNe Ia occur preferentially in star forming galaxies.

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