SN Ia 2016 jae中的星云H α发射
Nebular Halpha emission in SN Ia 2016jae
摘要：
人们普遍认为Ia型超新星（SN Ia）起源于CO白矮星（WD）的热核爆炸，在观测到的光谱中缺乏氢是一个显著的特征。在这里，我们介绍了SN 2016 jae，它在发现后不久获得的光谱中被归类为Ia型SN。SN的B波段峰值为-17.93 ± 0.34等，随后亮度快速下降，sBV为0.56 ± 0.06，推测Dm 15（B）为1.88 ± 0.10等。总体而言，SN表现为介于“正常”SNe Ia和非常暗淡的SNe Ia（如91 bg类SNe）之间的“过渡”事件。它的特点是，在峰值后+84天和+142天拍摄的两个后期光谱显示了一条窄的H α线（半峰全宽分别为~650和1000 kms-1）。这是继SN 2018 cqj/ATLAS 18 qtd和SN 2018 fhw/ASASSN-18 tb之后第三个低光度和快速衰减的Ia型SN，在100 IAS巡天中发现，在它们的星云相位光谱中显示出窄的H α发射线。我们认为，星云的H α发射起源于一个膨胀的富氢壳层（速度< 1000 kms-1）。氢壳层的速度太高，在一个共同的信封阶段产生，而它可能是一致的一些材料剥离富氢伴星在一个单一的简并祖星系统。然而，该剥离氢的导出质量为~0.002-0.003 Msun，这远小于这些场景的标准模型的预期质量（>0.1 Msun）。另一个合理的事件序列是一个弱的SN喷出物与H壳层的相互作用喷射光学厚风或新星样的爆发前几年的C/O WD祖超新星爆炸。
英文摘要：
There is a wide consensus that type Ia supernovae (SN Ia) originate from the thermonuclear explosion of CO white dwarfs (WD), with the lack of hydrogen in the observed spectra as a distinctive feature. Here, we present SN 2016jae, which was classified as a Type Ia SN from a spectrum obtained soon after the discovery. The SN reached a B-band peak of -17.93 +- 0.34 mag, followed by a fast luminosity decline with sBV 0.56 +- 0.06 and inferred Dm15(B) of 1.88 +- 0.10 mag. Overall, the SN appears as a "transitional" event between "normal" SNe Ia and very dim SNe Ia such as 91bg-like SNe. Its peculiarity is that two late-time spectra taken at +84 and +142 days after the peak show a narrow line of Halpha (with full width at half-maximum of ~650 and 1000 kms-1, respectively). This is the third low-luminosity and fast-declining Type Ia SN after SN 2018cqj/ATLAS18qtd and SN 2018fhw/ASASSN-18tb, found in the 100IAS survey that shows resolved narrow Halpha line in emission in their nebular-phase spectra. We argue that the nebular Halpha emission originates in an expanding hydrogen-rich shell (with velocity < 1000 kms-1). The hydrogen shell velocity is too high to be produced during a common envelope phase, while it may be consistent with some material stripped from an H-rich companion star in a single-degenerate progenitor system. However, the derived mass of this stripped hydrogen is ~0.002-0.003 Msun, which is much less than that expected (>0.1 Msun) for standard models for these scenarios. Another plausible sequence of events is a weak SN ejecta interaction with a H-shell ejected by optically thick winds or a nova-like eruption on the C/O WD progenitor some years before the supernova explosion.
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