arXivDaily arXiv每日学术速递 周一至周五更新
北美退伍军人节(Veterans Day),12 日无更新
arXiv 1406.2828astro-ph.HE
收藏

NGC 1058中Ic型超新星2007 gr的光学观测及其前身星性质

Optical Observations of the Type Ic Supernova 2007gr in NGC 1058 and Implications for the Properties of its Progenitor

Juncheng Chen, Xiaofeng Wang, Mohan Ganeshalingam, Jeffrey M. Silverman, Alexei V. Filippenko, Weidong Li, Ryan Chornock, Junzheng Li, Thea Steele

摘要:

我们对正常的Ic型超新星(SN)2007 gr进行了广泛的光学观测,从最大光之前的一周到之后的一年多。SN 2007 gr的光学光和颜色曲线与宽线Ic型SN 2002 ap非常相似,但光谱显示出显著的差异。SN 2007 gr的光谱特征是异常窄的线,突出的碳线,以及最大光后线速度的缓慢演变。最早的光谱(在t=-8天时拍摄)显示了氦的可能特征(He~I 5876,速度约为19,000 km s{-1})。此外,从早期星云光谱推断的[O I] 6300和6364线的较大强度比意味着爆炸后不久喷出物的不透明度较低。这些结果表明SN 2007 gr可能经历了一个双星系统中较小质量的沃尔夫-拉叶星(~ 8- 9 Msun)的能量较低的爆炸,通过爆炸前和爆炸后的哈勃太空望远镜图像分析祖星环境。在星云光谱中,[O~I] 6300和Mg~I] 4571谱线具有不对称的双峰轮廓。我们认为这两个峰值是由蓝移和静止帧分量贡献的。速度结构的相似性和两个分量的强度的不同演化有利于非球面爆炸与喷出物分布在环面或盘状几何形状,但在喷出物中的O和Mg有不同的分布。

英文摘要:

We present extensive optical observations of the normal Type Ic supernova (SN) 2007gr, spanning from about one week before maximum light to more than one year thereafter. The optical light and color curves of SN 2007gr are very similar to those of the broad-lined Type Ic SN 2002ap, but the spectra show remarkable differences. The optical spectra of SN 2007gr are characterized by unusually narrow lines, prominent carbon lines, and slow evolution of the line velocity after maximum light. The earliest spectrum (taken at t=-8 days) shows a possible signature of helium (He~I 5876 at a velocity of ~19,000 km s{-1}). Moreover, the larger intensity ratio of the [O I] 6300 and 6364 lines inferred from the early nebular spectra implies a lower opacity of the ejecta shortly after the explosion. These results indicate that SN 2007gr perhaps underwent a less energetic explosion of a smaller-mass Wolf-Rayet star (~ 8--9 Msun) in a binary system, as favored by an analysis of the progenitor environment through pre-explosion and post-explosion Hubble Space Telescope images. In the nebular spectra, asymmetric double-peaked profiles can be seen in the [O~I] 6300 and Mg~I] 4571 lines. We suggest that the two peaks are contributed by the blueshifted and rest-frame components. The similarity in velocity structure and the different evolution of the strength of the two components favor an aspherical explosion with the ejecta distributed in a torus or disk-like geometry, but inside the ejecta the O and Mg have different distributions.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑