SN 2020uem: a Possible Thermonuclear Explosion within a Dense Circumstellar Medium. I. The Nature of Type IIn/Ia-CSM SNe from Photometry and Spectroscopy-猫眼课题宝

DOI：

10.3847/1538-4357/acb5ec

发表时间：

2023-01

期刊：

The Astrophysical Journal

影响因子：

通讯作者：

中科院分区：

其他

文献类型：

作者：

K. Uno;K. Maeda;T. Nagao;T. Nakaoka;K. Motohara;A. Tajitsu;M. Konishi;S. Koyama;H. Takahashi;Masaomi Tanaka;H. Kuncarayakti;M. Kawabata;M. Yamanaka;K. Aoki;K. Isogai;K. Taguchi;M. Ogawa;K. Kawabata;Y. Yoshii;T. Miyata;R. Imazawa

我们对一颗超新星(SNIIn/Ia-CSM2020uem)进行了密集的跟踪观测，包括光度、光谱和偏振测量。在这篇文章中，我们报告了我们在光学/近红外(NIR)光度学和光谱学方面的观测结果。SN2020uem的最大V波段震级小于−19.5mag。光照曲线以0.75mAg/100d的∼速率缓慢下降。在后期(≳300d)，光照曲线呈现加速衰减(∼1.2mag/100d)。光谱显示出明显的氢发射谱线和可能与铁峰元素有关的宽广特征。此外，SN2020uem的H-α剖面具有较窄的P-Cygni剖面，其吸收极小值为∼100kM S−1。SN2020uem的Hα/Hβ比值(∼7)比SNE IIn的高，这表明它是一个密度更高的星周介质。近红外光谱显示在H和Ks带有连续谱过剩的Paschen和Brackett系列。我们得出结论，近红外超额排放来源于新形成的碳尘。尘埃质量(Md)和温度(Td)分别为(Md，Td)∼(4−7×10−5M⊙，1500-1600K)。我们讨论了SNE IIn/Ia-CSM与其他SNE Ia和相互作用SNE的观测性质的异同。特别是，SNE IIn/Ia-∼的∼4650ä和CSM附近的光谱特征比SNE Ia的光谱特征受到更大的抑制；这些谱线可能至少部分地由MgI和NaI贡献，并可能被大质量CSM引起的反向激波背后的高电离所抑制。

We have performed intensive follow-up observations of a Type IIn/Ia-CSM supernova (SN IIn/Ia-CSM), 2020uem, with photometry, spectroscopy, and polarimetry. In this paper, we report on the results of our observations focusing on optical/near-infrared (NIR) photometry and spectroscopy. The maximum V-band magnitude of SN 2020uem is less than −19.5 mag. The light curves decline slowly with a rate of ∼0.75 mag/100 days. In the late phase (≳300 days), the light curves show accelerated decay (∼1.2 mag/100 days). The optical spectra show prominent hydrogen emission lines and broad features possibly associated with Fe-peak elements. In addition, the Hα profile exhibits a narrow P-Cygni profile with an absorption minimum of ∼100 km s−1. SN 2020uem shows a higher Hα/Hβ ratio (∼7) than those of SNe IIn, which suggests a denser circumstellar medium (CSM). The NIR spectrum shows the Paschen and Brackett series with a continuum excess in the H and Ks bands. We conclude that the NIR excess emission originates from newly formed carbon dust. The dust mass (M d) and temperature (T d) are derived to be (M d, T d) ∼ (4−7 × 10−5 M ⊙, 1500–1600 K). We discuss the differences and similarities between the observational properties of SNe IIn/Ia-CSM and those of other SNe Ia and interacting SNe. In particular, spectral features around ∼4650 Å and ∼5900 Å of SNe IIn/Ia-CSM are more suppressed than those of SNe Ia; these lines are possibly contributed, at least partly, by Mg i] and Na i, and may be suppressed by high ionization behind the reverse shock caused by the massive CSM.

SN 2020uem: a Possible Thermonuclear Explosion within a Dense Circumstellar Medium. I. The Nature of Type IIn/Ia-CSM SNe from Photometry and Spectroscopy

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