最后时刻I：发光型II超新星2020 tlf之前的前体发射、包层膨胀和增强的质量损失
Final Moments I: Precursor Emission, Envelope Inflation, and Enhanced Mass loss Preceding the Luminous Type II Supernova 2020tlf
摘要：
我们目前的全色观测和建模的超新星（SN）2020tlf，第一个正常的II-P/L SN确认前体发射，检测到的年轻超新星实验瞬态调查与泛星1望远镜。在SN 2020tlf之前130天，在$riz-$波段检测到爆炸前排放，并以相对恒定的通量持续到第一次光照。在发现后不久，SN 2020 tlf的"闪光"光谱显示出显著的窄对称发射线（$v_w < 300$ km s $^{-1}$），这是由未受冲击的拱星物质（CSM）在爆炸前最后几周到几个月的祖星质量损失事件中脱落的光电离造成的。令人惊讶的是，这种新的显示前SN发射和相关的质量损失发生在RSG祖与ZAMS质量只有10 - 12 M $_{\odot}$，从星云光谱推断。用非LTE辐射传输代码CMFGEN和辐射流体动力学（RHD）代码HERACLES对光变曲线和多历元光谱进行建模，表明密集CSM限于$r \approx 10^{15}$ cm，质量损失率为$10^{-2}$ M $_{\odot}$ yr $^{-1}$。随后发光的光变曲线平台和持久的蓝色过量表明扩展的祖细胞，与带有$R_{\star} = 1100$ R $_{\odot}$的RSG模型兼容。从激波驱动的X射线和射电光度的极限得出的推论与这些结论是一致的，并建议在距离为$r \approx 5 \times 10^{15}$ cm时CSM密度为$ρ< 2 \times 10^{-16}$ g cm $^{-3}$，以及在更大距离时质量损失率为$\dot M<1.3 \times 10^{-5}\,\rm{M_{\odot}\,yr^{-1}}$。一个有前途的电源所观察到的前体发射是喷射的恒星物质的能量配置到恒星的信封作为一个结果，在氖/氧燃烧或核闪光从硅燃烧过程中发出的重力波。
英文摘要：
We present panchromatic observations and modeling of supernova (SN) 2020tlf, the first normal type II-P/L SN with confirmed precursor emission, as detected by the Young Supernova Experiment transient survey with the Pan-STARRS1 telescope. Pre-explosion emission was detected in $riz-$bands at 130 days prior to SN 2020tlf and persisted at relatively constant flux until first light. Soon after discovery, "flash" spectroscopy of SN 2020tlf revealed prominent narrow symmetric emission lines ($v_w < 300$ km s$^{-1}$) that resulted from the photo-ionization of unshocked circumstellar material (CSM) shedded in progenitor mass loss episodes in the final weeks to months before explosion. Surprisingly, this novel display of pre-SN emission and associated mass loss occurred in a RSG progenitor with ZAMS mass of only 10-12 M$_{\odot}$, as inferred from nebular spectra. Modeling of the light curve and multi-epoch spectra with the non-LTE radiative transfer code CMFGEN and radiation-hydrodynamical (RHD) code HERACLES suggests a dense CSM limited to $r \approx 10^{15}$ cm, and mass loss rate of $10^{-2}$ M$_{\odot}$ yr$^{-1}$. The subsequent luminous light-curve plateau and persistent blue excess indicates an extended progenitor, compatible with a RSG model with $R_{\star} = 1100$ R$_{\odot}$. Inferences from the limits on the shock-powered X-ray and radio luminosity are consistent with these conclusions and suggest a CSM density of $ρ< 2 \times 10^{-16}$ g cm$^{-3}$ for distances of $r \approx 5 \times 10^{15}$ cm, as well as a mass loss rate of $\dot M<1.3 \times 10^{-5}\,\rm{M_{\odot}\,yr^{-1}}$ at larger distances. A promising power source for the observed precursor emission is the ejection of stellar material following energy disposition into the stellar envelope as a result of gravity waves emitted during either neon/oxygen burning or a nuclear flash from silicon combustion.
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。
