SN 2017czd: A Rapidly Evolving Supernova from a Weak Explosion of a Type IIb Supernova Progenitor
SN 2017czd: A Rapidly Evolving Supernova from a Weak Explosion of a Type IIb Supernova Progenitor
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DOI：
10.3847/1538-4357/ab0dfe
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发表时间：
2019-04
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通讯作者：
T. Nakaoka;T. Moriya;Masaomi Tanaka;M. Yamanaka;K. Kawabata;K. Maeda;M. Kawabata;N. Kawahara;K. Itagaki;R. Ouchi;S. Blinnikov;N. Tominaga;M. Uemura
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作者：
T. Nakaoka;T. Moriya;Masaomi Tanaka;M. Yamanaka;K. Kawabata;K. Maeda;M. Kawabata;N. Kawahara;K. Itagaki;R. Ouchi;S. Blinnikov;N. Tominaga;M. Uemura
我们提出了快速演变的超新星（SN）2017czd的光学和近红外观测，显示出氢的特征。光学光变曲线呈现出一个短暂的平台期（R波段约13天），然后在平台期后20天迅速下降到4.5等。下降率大于任何标准SNe的下降率，并且接近快速演变的瞬变。V波段的峰值绝对星等为−16.8等，这在SNe IIP和快速演变瞬变的观测范围内。SN 2017czd的光谱清晰地显示了氢的特征，并与SNe IIP的光谱相似。然而，Hα线随时间变化不大，在下降阶段与SNe IIb相似。我们计算合成光变曲线使用SN IIb祖有16在零年龄的主序列，并演变成一个二元系统。具有低爆炸能量（5 × 1050 erg）和低56Ni质量（）的模型可以再现SN 2017czd中观察到的短平台阶段以及光变曲线的突然下降。我们的结论是，SN 2017czd可能是第一个从SN IIb祖先中识别出的弱爆炸。我们认为，一些快速发展的瞬变可以解释这样一个弱的祖爆炸，几乎没有富氢信封。
We present optical and near-infrared observations of the rapidly evolving supernova (SN) 2017czd that shows hydrogen features. The optical light curves exhibit a short plateau phase (∼13 days in the R-band) followed by a rapid decline by 4.5 mag ∼20 days after the plateau. The decline rate is larger than those of any standard SNe, and close to those of rapidly evolving transients. The peak absolute magnitude is −16.8 mag in the V band, which is within the observed range for SNe IIP and rapidly evolving transients. The spectra of SN 2017czd clearly show the hydrogen features and resemble those of SNe IIP at first. The Hα line, however, does not evolve much with time, and it becomes similar to those in SNe IIb at the decline phase. We calculate the synthetic light curves using a SN IIb progenitor that has 16 at the zero-age main sequence and evolves into a binary system. The model with a low explosion energy (5 × 1050 erg) and a low 56Ni mass ( ) can reproduce the short plateau phase, as well as the sudden drop of the light curve, as observed in SN 2017czd. We conclude that SN 2017czd might be the first weak explosion identified from a SN IIb progenitor. We suggest that some rapidly evolving transients can be explained by such a weak progenitor explosion with a barely hydrogen-rich envelope.