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arXiv 1407.4563astro-ph.HEastro-ph.SR
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电子捕获超新星在其前身风中爆炸

Electron-capture supernovae exploding within their progenitor wind

Takashi J. Moriya, Nozomu Tominaga, Norbert Langer, Ken'ichi Nomoto, Sergei I. Blinnikov, Elena I. Sorokina

摘要:

渐近巨星分支(AGB)中质量最大的恒星,也就是所谓的超级AGB星,被认为是在其简并的O+Ne+Mg核中被电子俘获而产生超新星(SNe)的。超级AGB恒星被认为具有高质量损失率的慢风,因此它们的风密度很高。因此,超AGB恒星的爆炸被认为发生在这种密集的风中。我们提供了第一个合成的光变曲线(LC)的爆炸现实的电子捕获超新星(ecSN)的祖先在他们的超级AGB风这样的事件。我们发现,早期LC,即复合波到达底部的富氢信封SN喷出物(高原阶段)之前,不受密集风。然而,在平台阶段之后,当考虑到超级AGB风时,光度仍然较高。我们将我们的结果与蟹状星云的前身SN 1054的历史LC进行了比较,并表明在普通的超级AGB风中ecSN的爆炸可以解释LC特征。我们的结论是,SN 1054可能是一个没有任何额外的极端质量损失的I In型SN,这是以前提出的解释其早期高光度所必需的。我们还表明,我们的LC匹配类型IIn SNe与早期的高原阶段(“类型IIn-P”),并建议他们在超级AGB风ecSNe。虽然某些ecSNe由于其较大的祖核半径而在光谱范围内是明亮的,但它们的X射线光度并不一定会像其他IIn型SNe那样明亮,因为它们的光学光度也是由相互作用提供动力的。因此,我们认为,光学明亮的X射线微弱的IIn型SNe可以出现从ecSNe。光学暗淡的IIn型超新星,如SN 2008 S,如果它们的富氢包层质量很小,也可能来自于ecSNe。其中一些可以观察到的'类型IIn-b' SNe由于小的富氢包层质量。

英文摘要:

The most massive stars on the asymptotic giant branch (AGB), so called super-AGB stars, are thought to produce supernovae (SNe) triggered by electron captures in their degenerate O+Ne+Mg cores. Super-AGB stars are expected to have slow winds with high mass-loss rates, so their wind density is high. The explosions of super-AGB stars are therefore presumed to occur in this dense wind. We provide the first synthetic light curves (LCs) for such events by exploding realistic electron-capture supernova (ecSN) progenitors within their super-AGB winds. We find that the early LC, i.e. before the recombination wave reaches the bottom of the H-rich envelope of SN ejecta (the plateau phase), is not affected by the dense wind. However, after the plateau phase, the luminosity remains higher when the super-AGB wind is taken into account. We compare our results to the historical LC of SN 1054, the progenitor of the Crab Nebula, and show that the explosion of an ecSN within an ordinary super-AGB wind can explain the LC features. We conclude that SN 1054 could have been a Type IIn SN without any extra extreme mass loss which was previously suggested to be necessary to account for its early high luminosity. We also show that our LCs match Type IIn SNe with an early plateau phase (`Type IIn-P') and suggest that they are ecSNe within super-AGB winds. Although some ecSNe can be bright in the optical spectral range due to the large progenitor radius, their X-ray luminosity from the interaction does not necessarily get as bright as other Type IIn SNe whose optical luminosities are also powered by the interaction. Thus, we suggest that optically-bright X-ray-faint Type IIn SNe can emerge from ecSNe. Optically-faint Type IIn SNe, such as SN 2008S, can also originate from ecSNe if their H-rich envelope masses are small. Some of them can be observed as `Type IIn-b' SNe due to the small H-rich envelope mass.

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