标题： 明亮的II型超新星2023ixf在M101：早期光谱和近红外光变曲线的快速分析 显示英文标题

标题： Bright Type II Supernova 2023ixf in M101: A Quick Analysis of the Early-Stage Spectra and Near-Infrared Light Curves

摘要： 我们对明亮的II型超新星（SN II）2023ixf在显著的近邻旋涡星系M101中的低分辨率（$R=1000$）光学光谱和近红外光变曲线进行了早期分析，这些数据是从$t=1.7$到$8.0$天获得的。我们的第一张光谱显示了明显的巴尔末线系发射特征、He~{\sc 二}、N~{\sc iii}、C~{\sc iv}和N~{\sc iv}，并具有强烈的蓝连续谱。与显示出闪光电离特征的II型超新星相比，我们认为该超新星可能被归类为高光度的II型超新星，其周围介质富含氮/氦（CSM），例如SNe 2014G、2017ahn和2020pni。 H~{$\alpha$}发射线可以暂且用一个速度为$<300$km~s$^{-1}$的较窄组分和一个速度为$\sim2200$km~s$^{-1}$的较宽组分来解释。 近红外光变曲线与另一个明亮的 SN 2017ahn 的光变曲线一致，其绝对星等位于 SNe II 光度分布的明亮端。 这些观测事实支持 SN 2023ixf 与显示出致密氮/氦富集的 CSM 证据的高光度 SNe II 一致。 显示英文摘要

摘要： We present early-stage analyses of low-resolution ($R=1000$) optical spectra and near-infrared light curves of the bright Type II supernova (SN II) 2023ixf in the notable nearby face-on spiral galaxy M101, which were obtained from $t=1.7$ to $8.0$ d. Our first spectrum showed remarkable emission features of Balmer series, He~{\sc ii}, N~{\sc iii}, C~{\sc iv}, and N~{\sc iv} with a strong blue continuum. Compared with the SNe II showing flash-ionized features, we suggest that this SN could be categorized into the high-luminosity SNe II with a nitrogen/helium-rich circumstellar material (CSM), e.g., SNe 2014G, 2017ahn, and 2020pni. The H~{$\alpha$} emission line can be tentatively explained by a narrower component with a velocity of $<300$ km~s$^{-1}$ and a broader one with $\sim2200$ km~s$^{-1}$. The near-infrared light curves were well consistent with those of the another luminous SN 2017ahn, and its absolute magnitudes locate on the bright end in the luminosity distribution of SNe II. These observational facts support that SN 2023ixf is well consistent with high-luminosity SNe II showing evidences of a dense nitrogen/helium-rich CSM.