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arXiv 1712.03370astro-ph.SRastro-ph.GA
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SN2012ab:一颗特殊的具有非球形星周物质的I型In超新星

SN2012ab: A Peculiar Type IIn Supernova with Aspherical Circumstellar Material

Christopher Bilinski, Nathan Smith, G. Grant Williams, Paul Smith, WeiKang Zheng, Melissa L. Graham, Jon C. Mauerhan, Jennifer E. Andrews, Alexei V. Filippenko,… 展开作者

Christopher Bilinski, Nathan Smith, G. Grant Williams, Paul Smith, WeiKang Zheng, Melissa L. Graham, Jon C. Mauerhan, Jennifer E. Andrews, Alexei V. Filippenko, Carl Akerlof, E. Chatzopoulos, Jennifer L. Hoffman, Leah Huk, Douglas C. Leonard, G. H. Marion, Peter Milne, Robert M. Quimby, Jeffrey M. Silverman, Jozsef Vinkó, J. Craig Wheeler, Fang Yuan

摘要:

我们介绍了超新星(SN)2012 ab的测光,光谱和分光偏振测量,主要是在发现后的$\sim 300$天内获得的。SN 2012 ab是在旋涡星系2MASXJ 12224762 +0536247的核心附近发现的一个IIn型事件。虽然它的光变曲线与SN 1998 S相似,但它的光谱演化却不一样。我们看到CSM相互作用的迹象,在强烈的中等宽度的发射功能,高亮度(峰值在绝对星等$M=-19.5$),并在光谱中缺乏广泛的吸收功能。H PDMATHAMO发射经历了一个特殊的跃迁。在早期,它显示出一个宽的蓝色发射翼到$-14{,}000$ km $\mathrm{s^{-1}}$和一个截断的红色翼。然后在后期($>$ 100 $\,$天),它显示出一个截断的蓝色机翼和一个非常宽的红色发射机翼,大约$+20{,}000$ km $\mathrm{s^{-1}}$。这种晚期的宽红翼可能产生于反向激波。光谱还显示了一个不对称的中间宽度H $α$组件,在较晚的时候,在红色的一面有较强的发射。非对称轮廓的演变需要在远距离CSM中的高度非球面的密度结构。我们的光谱偏振数据还表明非球面性与强的连续极化的$\sim 1-3$ %和H $α$线的去极化,表明非球面性在CSM在一个水平,可与其他SNe IIn。我们估计$v_{\rm pre} = 100$ $\,$ km $\,$ $\mathrm{s^{-1}}$的质量损失率为$\dot{M} = 0.050\, {\rm M}_{\odot}\,\mathrm{yr^{-1}}$,至少在SN之前的75 $\,$。SN 2012ab的CSM强烈偏离轴对称,可能表明其前身是一个正在经历爆发性质量损失的偏心双星系统。

英文摘要:

We present photometry, spectra, and spectropolarimetry of supernova (SN) 2012ab, mostly obtained over the course of $\sim 300$ days after discovery. SN 2012ab was a Type IIn (SN IIn) event discovered near the nucleus of spiral galaxy 2MASXJ12224762+0536247. While its light curve resembles that of SN 1998S, its spectral evolution does not. We see indications of CSM interaction in the strong intermediate-width emission features, the high luminosity (peak at absolute magnitude $M=-19.5$), and the lack of broad absorption features in the spectrum. The H$α$ emission undergoes a peculiar transition. At early times it shows a broad blue emission wing out to $-14{,}000$ km $\mathrm{s^{-1}}$ and a truncated red wing. Then at late times ($>$ 100$\,$days) it shows a truncated blue wing and a very broad red emission wing out to roughly $+20{,}000$ km $\mathrm{s^{-1}}$. This late-time broad red wing probably arises in the reverse shock. Spectra also show an asymmetric intermediate-width H$α$ component with stronger emission on the red side at late times. The evolution of the asymmetric profiles requires a density structure in the distant CSM that is highly aspherical. Our spectropolarimetric data also suggest asphericity with a strong continuum polarization of $\sim 1-3$% and depolarization in the H$α$ line, indicating asphericity in the CSM at a level comparable to that in other SNe IIn. We estimate a mass-loss rate of $\dot{M} = 0.050\, {\rm M}_{\odot}\,\mathrm{yr^{-1}}$ for $v_{\rm pre} = 100$$\,$km$\,$$\mathrm{s^{-1}}$ extending back at least 75$\,$yr prior to the SN. The strong departure from axisymmetry in the CSM of SN 2012ab may suggest that the progenitor was an eccentric binary system undergoing eruptive mass loss.

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