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arXiv 1703.03084astro-ph.HEastro-ph.SR
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由风加速引起的超新星祖先的立即稠密的星周环境:它对超新星光变曲线的影响

Immediate dense circumstellar environment of supernova progenitors caused by wind acceleration: its effect on supernova light curves

Takashi J. Moriya, Sung-Chul Yoon, Götz Gräfener, Sergei I. Blinnikov

摘要:

IIP型超新星的前身通常被致密的星周介质所包围,这可能是由于前身在爆炸前不久的质量损失增强。以前的光变曲线研究表明,质量损失率提高到约0.1 Msun/年,假设风速恒定。然而,在恒星附近的星周介质的密度可以远高于以前推断的一个给定的质量损失率,如果考虑到风的加速度。以SN 2013 fs为例,我们发现风加速度对从IIP型超新星早期光变曲线估算质量损失率有很大的影响。我们进行数值计算的超新星喷出物和拱星介质之间的相互作用,具有恒定的质量损失率,但与β法风速剖面。我们发现,SN 2013 fs的前身的质量损失率在爆炸前不久,这是推断为~ 0.1 Msun/yr的恒定风速为10 km/s的光变曲线模型,可以低至~ 1 e-3 Msun/yr的相同的终端风速为10 km/s,但风速剖面β ~ 5。在这两种情况下,星周介质的质量是相似的(~ 0.5 Msun)。因此,在我们的解释中,祖先的质量损失增加的开始是在爆炸前100年左右,而不是几年。我们的结果表明,II型超新星祖先的直接致密环境可能会受到风加速的显著影响。

英文摘要:

Type IIP supernova progenitors are often surrounded by dense circumstellar media that may result from mass-loss enhancement of the progenitors shortly before their explosions. Previous light-curve studies suggest that the mass-loss rates are enhanced up to ~ 0.1 Msun/yr, assuming a constant wind velocity. However, density of circumstellar media at the immediate stellar vicinity can be much higher than previously inferred for a given mass-loss rate if wind acceleration is taken into account. We show that the wind acceleration has a huge impact when we estimate mass-loss rates from early light curves of Type IIP supernovae by taking SN 2013fs as an example. We perform numerical calculations of the interaction between supernova ejecta and circumstellar media with a constant mass-loss rate but with a beta-law wind velocity profile. We find that the mass-loss rate of the progenitor of SN 2013fs shortly before the explosion, which was inferred to be ~ 0.1 Msun/yr with a constant wind velocity of 10 km/s by a previous light-curve modeling, can be as low as ~ 1e-3 Msun/yr with the same terminal wind velocity of 10 km/s but with a wind velocity profile with beta ~ 5. In both cases, the mass of the circumstellar medium is similar (~ 0.5 Msun). Therefore, the beginning of the progenitor's mass-loss enhancement in our interpretation is ~ 100 years before the explosion, not several years. Our result indicates that the immediate dense environment of Type II supernova progenitors may be significantly influenced by wind acceleration.

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