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arXiv 1004.2791astro-ph.HEastro-ph.SR
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核塌缩超新星与星周壳层碰撞的数值模型

Numerical models of collisions between core-collapse supernovae and circumstellar shells

Allard Jan van Marle, Nathan Smith, Stanley P. Owocki, Bob van Veelen

摘要:

最近对发光的IIn型超新星(SNe)的观测提供了令人信服的证据,证明它们的祖先周围有巨大的拱星壳。在本文中,我们调查如何影响SN光变曲线的属性进行数值模拟的膨胀SN和拱壳弹出几年前核心崩溃之间的相互作用。我们的参数研究探讨了如何紧急光度取决于一系列的拱壳质量,速度,几何形状,风的质量损失率,以及在SN质量和能量的变化。我们发现壳层质量是最重要的参数,在这个意义上,更高的壳层质量(或更高的M-shell/M-SN比)导致更高的峰值亮度和更高的效率,在转换冲击能量到可见光。如果壳层速度慢或者SN喷出物速度非常快,则质量较低的壳层也可以导致高峰值亮度,但仅持续很短的时间。维持高光度持续时间超过100天,需要大量的拱壳数量级为10 M太阳或更高。这再次证实了以前SN前壳和发光蓝变星(LBV)巨大爆发产生的壳之间的比较,尽管这些爆发的物理机制仍然不确定。光变曲线的形状和观测到的壳层速度可以帮助诊断星周壳层的近似大小和密度,并且有可能区分具有多波长光变曲线的球形和双极壳层。这些模型仅仅是说明性的。当然,我们可以通过增加爆炸能量和壳层质量来获得更高的亮度和更长的光变曲线。

英文摘要:

Recent observations of luminous Type IIn supernovae (SNe) provide compelling evidence that massive circumstellar shells surround their progenitors. In this paper we investigate how the properties of such shells influence the SN lightcurve by conducting numerical simulations of the interaction between an expanding SN and a circumstellar shell ejected a few years prior to core collapse. Our parameter study explores how the emergent luminosity depends on a range of circumstellar shell masses, velocities, geometries, and wind mass-loss rates, as well as variations in the SN mass and energy. We find that the shell mass is the most important parameter, in the sense that higher shell masses (or higher ratios of M_shell/M_SN) lead to higher peak luminosities and higher efficiencies in converting shock energy into visual light. Lower mass shells can also cause high peak luminosities if the shell is slow or if the SN ejecta are very fast, but only for a short time. Sustaining a high luminosity for durations of more than 100 days requires massive circumstellar shells of order 10 M_sun or more. This reaffirms previous comparisons between pre-SN shells and shells produced by giant eruptions of luminous blue variables (LBVs), although the physical mechanism responsible for these outbursts remains uncertain. The lightcurve shape and observed shell velocity can help diagnose the approximate size and density of the circumstellar shell, and it may be possible to distinguish between spherical and bipolar shells with multi-wavelength lightcurves. These models are merely illustrative. One can, of course, achieve even higher luminosities and longer duration light curves from interaction by increasing the explosion energy and shell mass beyond values adopted here.

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