Spectra and phototometry of type IIn supernova SN 1997eg are used to determine properties of the circumstellar gas lost by the presupernova during the latest 200 years before the explosion. The analysis of narrow H$α$ and [Fe X] 6374 Å results in the wind velocity $u = 20$ km/s, significantly lower than the earlier accepted value (160 km/s) upon the bases of the radial velocity of a blue absorption wing of the narrow H$α$. That high velocity of the wind in our picture is related to the preshock gas accelerated by the cosmic ray precursor. The modelling of the circumstellar interaction results in the wind density parameter $\dot{M}/u$ that being combined with the wind velocity suggests the presupernova mass loss rate of $1.6\cdot10^{-3} M_{\odot}$ yr$^{-1}$. The wind density is consistent with the [Fe X] 6374 Å luminosity. The model H$α$ luminosity also agrees with the observational value. Recovered wind properties indicate that the presupernova at the final evolutionary stage was a massive red supergiant with a high mass loss rate, but not the LBV-supergiant as suggested earlier.
Little Red Dots as Intermediate Mass, Super-Eddington Engines: Insights from Type IIn Supernovae and The 1837-1856 Great Eruption of $η$ Carinae
MIT Kavli Institute for Astrophysics and Space Research（麻省理工学院卡弗里天体物理与空间研究所）；Institute for Astronomy, University of Hawai‘i（夏威夷大学天文学研究所）；Institute of Science and Technology Austria (ISTA)（奥地利科学技术研究所）；Center for Astrophysics, Harvard & Smithsonian（哈佛-史密森尼天体物理中心）；Max-Planck-Institut für Astronomie（马克斯·普朗克天体物理学研究所）；Department of Astronomy & Astrophysics, University of Chicago（芝加哥大学天文与天体物理系）；Kavli Institute for Cosmological Physics, University of Chicago（芝加哥大学卡弗里宇宙物理学研究所）；Department of Astronomy, The University of Texas at Austin（德克萨斯大学奥斯汀分校天文系）；Cosmic Frontier Center, The University of Texas at Austin（德克萨斯大学奥斯汀分校宇宙前沿中心）
A Long-Duration Luminous Type IIn Supernova KISS15s: Strong Recombination Lines from the Inhomogeneous Ejecta-CSM Interaction Region and Hot Dust Emission from Newly Formed Dust
我们报告了在木曾超新星巡天（KISS）过程中在一个红移z=0.038的低质量恒星形成星系中发现的一颗类SN 1988 Z IIn型超新星KISS 15 s。KISS 15 s显示出长时间的光学连续谱和发射线光变曲线，表明KISS 15 s是由膨胀的喷出物和致密的星周介质（CSM）之间的持续相互作用提供动力的。H $α$发射线轮廓可以分解为四个高斯的窄，中间，蓝移中间，和广泛的速度宽度分量，与半高全宽$\lesssim 100$，$\sim 2,000$，和$\sim 14,000$ km s ${}^{-1}$的窄，中间，和广泛的组件，分别。蓝移的中间分量的存在下，其中相对于系统速度的视线速度约为$-5,000$ km s ${}^{-1}$，表明喷出物-CSM相互作用区域具有不均匀的形态和各向异性的膨胀速度。我们发现，KISS 15 s显示出不断增加的红外连续辐射，这可以解释为热尘埃热发射的$T \sim 1,200$ K从新形成的尘埃在一个冷的，致密的壳层中的喷出物CSM相互作用区域。从热光度推断出的前身质量损失率是$\dot{M} \sim 0.4 M_{\odot} \text{yr}^{-1} (v_{w}/40 \text{km}~\text{s}^{-1})$，其中$v_{w}$是前身的恒星风速度。这意味着KISS 15 s的前身是一颗红超巨星或一颗发光的蓝色变星，在…
