SN 2015 bf：一颗快速衰减的II型超新星，具有闪光电离特征
SN 2015bf: a fast declining type II supernova with flash-ionised signatures
摘要：
我们目前的光学和紫外测光，以及光谱，II型超新星（SN）2015 bf。我们的观测涵盖了爆炸后从$\sim 2$到$\sim 200$ d的阶段。第一个光谱的特点是一个蓝色的连续与黑体温度为$\sim 24,000$ K和闪光电离发射线。大约一周后，SN 2015 bf的光谱就像普通SN II一样演化。从H $α$窄发射组分的发光度可以推断其质量损失率大于$\sim 3.7\times10^{-3}\,{\rm M_\odot\,yr^{-1}}$。爆炸后第一周内闪光特征的消失表明星周物质被限制在$\sim 6 \times 10^{14}$厘米范围内。因此，我们认为SN 2015 bf的前身在超新星爆炸前不久经历了剧烈的质量损失。多波段光变曲线显示SN 2015 bf有一个高的峰值亮度，绝对视星等为$M_V = -18.11 \pm 0.08$ mag，并且在最大光之后的$\sim 50$ d内有一个快速的峰值后衰减，$V$ -波段衰减为$1.22 \pm 0.09$ mag。此外，SN 2015 bf的$R$带尾光度比SNe~II的弱1- 2等，说明在爆炸过程中合成了少量的${\rm ^{56}Ni}$（$\sim 0.009\,{\rm M_\odot}$）.如此低的镍质量表明SN 2015 bf的前身可能是一颗超渐近巨星分支恒星，由于电子捕获而坍缩。
英文摘要：
We present optical and ultraviolet photometry, as well as optical spectra, for the type II supernova (SN) 2015bf. Our observations cover the phases from $\sim 2$ to $\sim 200$ d after explosion. The first spectrum is characterised by a blue continuum with a blackbody temperature of $\sim 24,000$K and flash-ionised emission lines. After about one week, the spectra of SN 2015bf evolve like those of a regular SN II. From the luminosity of the narrow emission component of H$α$, we deduce that the mass-loss rate is larger than $\sim 3.7\times10^{-3}\,{\rm M_\odot\,yr^{-1}}$. The disappearance of the flash features in the first week after explosion indicates that the circumstellar material is confined within $\sim 6 \times 10^{14}$ cm. Thus, we suggest that the progenitor of SN 2015bf experienced violent mass loss shortly before the supernova explosion. The multiband light curves show that SN 2015bf has a high peak luminosity with an absolute visual magnitude $M_V = -18.11 \pm 0.08$ mag and a fast post-peak decline with a $V$-band decay of $1.22 \pm 0.09$ mag within $\sim 50$ d after maximum light. Moreover, the $R$-band tail luminosity of SN 2015bf is fainter than that of SNe~II with similar peak by 1--2 mag, suggesting a small amount of ${\rm ^{56}Ni}$ ($\sim 0.009\,{\rm M_\odot}$) synthesised during the explosion. Such a low nickel mass indicates that the progenitor of SN 2015bf could be a super-asymptotic-giant-branch star that collapsed owing to electron capture.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
