Calcium-rich Transient SN 2019ehk in a Star-forming Environment: Yet Another Candidate for a Precursor of a Double Neutron-star Binary-猫眼课题宝

DOI：

10.3847/1538-4357/abe765

发表时间：

2020-05

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：

T. Nakaoka;K. Maeda;M. Yamanaka;Masaomi Tanaka;M. Kawabata;T. Moriya;K. Kawabata;N. Tominaga;K. Takagi;F. Imazato;T. Morokuma;S. Sako;R. Ohsawa;T. Nagao;Jiachen Jiang;U. Burgaz;K. Taguchi;M. Uemura;H. Akitaya;M. Sasada;K. Isogai;M. Otsuka;H. Maehara

我们提出了SN 2019ehk的光学和近红外观测，它最初被报道为Ib型超新星（SN）。我们表明，它演变成一个富钙瞬态根据其光谱特性和演化在后期阶段。然而，它显示出一些不同于典型的富钙瞬变的特性：光变曲线中的第一个短持续时间的峰值，高峰亮度，以及与恒星形成环境的关联。事实上，这些特征中的一些与iPTF14gqr和iPTF16hgs共享，iPTF14gqr和iPTF16hgs是一类特殊的核心塌陷SNe的候选者：所谓的超剥离包络SNe，即，一种相对低质量的He（或C+O）星星在双星中爆炸，是短周期双中子星星（NS）双星的先驱。估计的喷出物质量（0.4兆焦耳）和爆炸能量（1.7 × 1050尔格）与这一假设一致。对第一个峰的分析表明，在祖星附近存在致密的星周物质，这意味着CCSN的起源。基于这一分析，我们认为SN 2019 ehk是低质量He星星爆炸的另一个候选者。它可能会创建一个双NS二进制文件，但有很大的分离。这些候选人的低质量剥离信封SNe，包括超剥离信封SN候选人，似乎形成一个亚群之间的富钙瞬变，与年轻的人口。我们认为区分这一种群的关键是它们光变曲线中的早期第一个峰值。

We present optical and near-infrared observations of SN 2019ehk, which was initially reported as a Type Ib supernova (SN). We show that it evolved to a Ca-rich transient according to its spectral properties and evolution in late phases. However, it shows a few properties distinct from those of the canonical Ca-rich transients: a short-duration first peak in the light curve, high peak luminosity, and association with a star-forming environment. Indeed, some of these features are shared with iPTF14gqr and iPTF16hgs, which are candidates for a special class of core-collapse SNe: the so-called ultra-stripped envelope SNe, i.e., a relatively low-mass He (or C+O) star explosion in a binary as a precursor of short-period double neutron star (NS) binaries. The estimated ejecta mass (0.4M ⊙) and explosion energy (1.7 × 1050 erg) are consistent with this scenario. The analysis of the first peak suggests the existence of dense circumstellar material in the vicinity of the progenitor, implying a CCSN origin. Based on this analysis, we suggest SN 2019ehk is another candidate for a low-mass He star explosion. It might create a double NS binary, but with a wide separation. These candidates for low-mass stripped envelope SNe, including ultra-stripped envelope SN candidates, seem to form a subpopulation among Ca-rich transients, associated with young population. We propose that the key to distinguishing this population is the early first peak in their light curves.

Calcium-rich Transient SN 2019ehk in a Star-forming Environment: Yet Another Candidate for a Precursor of a Double Neutron-star Binary

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