Mazzali Paolo A, Kawabata Koji S, Maeda Keiichi, Nomoto Ken'ichi, Filippenko Alexei V, Ramirez-Ruiz Enrico, Benetti Stefano, Pian Elena, Deng Jinsong, Tominaga Nozomu, Ohyama Youichi, Iye Masanori, Foley Ryan J, Matheson Thomas, Wang Lifan, Gal-Yam Avishay
Department of Astronomy, School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.
Science. 2005 May 27;308(5726):1284-7. doi: 10.1126/science.1111384.
Type Ic supernovae, the explosions after the core collapse of massive stars that have previously lost their hydrogen and helium envelopes, are particularly interesting because of their link with long-duration gamma ray bursts. Although indications exist that these explosions are aspherical, direct evidence has been missing. Late-time observations of supernova SN 2003jd, a luminous type Ic supernova, provide such evidence. Recent Subaru and Keck spectra reveal double-peaked profiles in the nebular lines of neutral oxygen and magnesium. These profiles are different from those of known type Ic supernovae, with or without a gamma ray burst, and they can be understood if SN 2003jd was an aspherical axisymmetric explosion viewed from near the equatorial plane. If SN 2003jd was associated with a gamma ray burst, we missed the burst because it was pointing away from us.
Ic型超新星是大质量恒星在先前失去氢和氦包层后核心坍缩引发的爆炸，因其与长持续时间伽马射线暴的联系而格外引人关注。尽管有迹象表明这些爆炸是非球对称的，但一直缺少直接证据。对明亮的Ic型超新星SN 2003jd的晚期观测提供了这样的证据。近期昴星团望远镜和凯克望远镜的光谱显示，中性氧和镁的星云谱线呈现双峰轮廓。这些轮廓与已知的有或没有伽马射线暴的Ic型超新星不同，如果SN 2003jd是从赤道平面附近观测到的非球对称轴对称爆炸，就能解释这些轮廓。如果SN 2003jd与一次伽马射线暴有关联，那我们之所以没观测到这次暴，是因为它的方向背离我们。
