Searching for a Companion Star of Tycho's Type Ia Supernova with Optical Spectroscopic Observations
Searching for a Companion Star of Tycho's Type Ia Supernova with Optical Spectroscopic Observations
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DOI：
10.1093/pasj/59.4.811
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发表时间：
2006-08
影响因子：
2.3
通讯作者：
Y. Ihara;Jin Ozaki;M. Doi;T. Shigeyama;N. Kashikawa;Y. Komiyama;T. Hattori
中科院分区：
文献类型：
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作者：
Y. Ihara;Jin Ozaki;M. Doi;T. Shigeyama;N. Kashikawa;Y. Komiyama;T. Hattori
我们报告了第谷超新星遗迹（SNR Tycho）的光度和光谱观测结果，以寻找Ia型超新星（SN Ia）的伴星。通过斯巴鲁望远镜上的super - cam的光度观测，我们已经在光谱中发现了亮度超过22等（V波段）的恒星，它们位于SNR第谷中心周围半径为30英寸的圆形区域内。如果年轻超新星残留物的喷出物，如SNR第谷，有足够的铁I，我们应该能够探测到3720 \AA和3860 \AA的吸收线，这些吸收线与伴星光谱中铁I基态的转变有关。为了利用这些铁离子的特征吸收谱线来识别SN Ia的伴星，我们利用斯巴鲁望远镜上的FOCAS对它们的目标进行了光学低分辨率光谱分析。在我们的光谱观测中，我们获得了信噪比第谷区域17颗恒星的光谱，并与模板恒星光谱进行了比较。我们从3720 \AA的两颗恒星探测到明显的吸收谱线。由于它们的吸收谱线宽度很宽，很可能是由于第谷信噪比膨胀的喷出物中的Fe - 1引起的。然而，在观测到的吸收剖面中，没有一颗恒星显示出清晰的红翼，尽管在信噪比背景中的恒星应该会显示出这一点。因此，我们提出了另一种解释，即探测到的吸收线可能是由恒星的特殊性引起的。一颗名为第谷(E)的恒星的吸收线位于3720 \AA，其投影位置接近第谷信噪比的中心。根据我们的观测，第谷(E)是第谷超新星伴星的新候选者。
We report our first results of photometric and spectroscopic observations for Tycho's supernova remnant (SNR Tycho) to search for the companion star of a type Ia supernova (SN Ia). From photometric observations using Suprime-Cam on the Subaru Telescope, we have picked up stars brighter than 22 mag (in $V$-band) for spectroscopy, which are located within a circular region with the radius of 30" around the center of SNR Tycho. If the ejecta of young supernova remnants, such as SNR Tycho, have a sufficient amount of Fe I, we should be able to detect absorption lines at 3720 \AA and 3860 \AA associated with transitions from the ground state of Fe I in the spectrum of the companion star. To identify the companion star of a SN Ia using these characteristic absorption lines of Fe I, we made optical low-resolution spectroscopy of their targets using FOCAS on the Subaru Telescope. In our spectroscopic observations, we obtained spectra of 17 stars in the SNR Tycho region and compare them with template stellar spectra. We detect significant absorption lines from two stars at 3720 \AA. Since widths of their absorption lines are broad, it is likely that the detected absorptions are due to Fe I in the expanding ejecta of SNR Tycho. However, none of stars exhibits a clear red wing in the observed profiles of the absorption, though a star in the background of the SNR should show it. Hence, we suggest another interpretation that the detected absorption lines might be caused by the peculiarity of stars. A star named Tycho(E) has the absorption line at 3720 \AA and its projected position is close to the center of SNR Tycho. Based on our observations, Tycho(E) is a new candidate as the companion star of Tycho's supernova.