Ib和Ic超新星：修订间差异

[[超新星]]的分类是依据在光谱中是否缺乏[[氢|氫]]的[[光學頻譜|光谱]]线。与II型超新星比较，I型是欠缺[[氢|氫]]线的。与著名的[[Ia超新星]]不同，Ib的谱线中还缺少波长为635.5&nbsp;[[纳米|奈米]]的单一离子[[硅|矽]][[譜線|吸收线]]。比较Ib超新星的年齡，它也显示出比Ia型更明显的[[氦]]谱线。总而言之，Ib型超新星的谱线中包含有[[氧]]、[[鈣]]、和[[鎂]]的谱线。对照的Ia型，主要的谱线则来自于[[铁]]。<ref name="SAO">{{cite web | url = http://cosmos.swin.edu.au/entries/typeibsupernovaspectra/typeibsupernovaspectra.html?e=1 | title = Type Ib Supernova Spectra | publisher = Swinburne University of Technology | accessdate = 2007-02-08 | | | }}</ref>

在成为超新星之前，一颗大质量恒星演变出像洋蔥一样的层次。不同层次进行著不同元素的核融合反应，最外层是氫，向内依序是氦、碳、氧等等。因此，当外层的氫流失之后，接下来露在最外层的就是以氦为主的层次（混合著其他的元素）。当一颗大质量恒星发展到非常热，且恒星风造成巨大的质量损失时，这种情狀就会发生。质量非常巨大（25倍太阳质量或更大）的恒星每年可以经由恒星风流失10⁻⁵太阳质量以上的质量（或是每100,000年损失一个太阳的质量）<ref>{{cite journal | author=L. M. Dray, C. A. Tout, A. I. Karakas, J. C. Lattanzio | title=Chemical enrichment by Wolf-Rayet and asymptotic giant branch stars | journal=Monthly Notice of the Royal Astronomical Society | year=2003 | volume=338 | pages=973-989 | url=http://adsabs.harvard.edu/abs/2003MNRAS.338..973D | accessdate=2007-02-08 | | | }}</ref>。

Ib和Ic超新星的前身因为强烈的[[恒星风]]，或是因为与邻近伴星的交互作用，本身流失的质量可以达到3至4个[[太阳质量]] <ref>{{cite conference | last = Pols | first = Onno | title = Close Binary Progenitors of Type Ib/Ic and IIb/II-L Supernovae | booktitle = Proceedings of The Third Pacific Rim Conference on Recent Development on Binary Star Research | pages = 153-158 | date = 26 October - 1 November, 1995 | location = Chiang Mai, Thailand | url = http://adsabs.harvard.edu/abs/1997rdbs.conf..153P | accessdate = 2006-11-29 | | | }}</ref><ref name="woosley95">{{cite conference | author=Woosley, S. E.; Eastman, R. G. | title =Type Ib and Ic Supernovae: Models and Spectra | booktitle =Proceedings of the NATO Advanced Study Institute | pages =821 | publisher =Dordrecht: Kluwer Academic Publishers | date =June 20-30, 1995 | location =Begur, Girona, Spain | url =http://adsabs.harvard.edu/abs/1997thsu.conf..821W | accessdate = 2007-05-09 }}</ref>。Ib超新星被认为是大质量的[[沃尔夫-拉叶星]]塌缩造成的；也有些证据显示有一些Ic超新星的前身可能是[[伽马射线暴|γ射线爆发]]（GRB），虽然也有人相信任何氫被剝离的Ib和Ic超新星都来自GRB－与爆炸的几何形狀有关<ref>{{cite journal | author=S. D. Ryder, E. M. Sadler, R. Subrahmanyan, K. W. Weiler, N. Panagia, C. Stockdale | title=Modulations in the radio light curve of the Type IIb supernova 2001ig: evidence for a Wolf-Rayet binary progenitor? | journal=Monthly Notices of the Royal Astronomical Society | year=2004 | volume=349 | issue=3 | pages=1093-1100 | url=http://adsabs.harvard.edu/abs/2004MNRAS.349.1093R | accessdate=2007-02-01 | | | }}</ref>。

由生成的比率来看，需要大质量恒星才能形成的Ib和Ic超新星是非常罕见的，远低于[[II型超新星]]的生成率<ref>{{cite web | author = E. M. Sadler, D. Campbell | year = 1997 | url = http://www.atnf.csiro.au/pasa/14_2/sadler/paper/node4.html | title = A first estimate of the radio supernova rate | publisher = Astronomical Society of Australia | accessdate = 2007-02-08 | | | }}</ref>。它们通常都出现在恒星形成的区域，并且未曾在[[橢圆星系]]中被发现过<ref name="woosley95" />，因为它们分享相似的传动机制，所以Ib、Ic和不同类型的[[II型超新星]]都称为核心塌缩型超新星。

Ib超新星的光度曲线（光度相对于时间的描绘图）虽然有不同形式的变化，在某些情況下与[[Ia超新星]]非常相似。但不无论如何，Ib超新星光度曲线的峰值较低，而且颜色偏红。在[[红外线]]部分的光谱，Ib的光度曲线类似于II-L的光度曲线（参见[[超新星]]）<ref>{{cite journal | last=Tsvetkov | first=D. Yu. | title=Light curves of type Ib supernova: SN 1984l in NGC 991 | journal=Soviet Astronomy Letters | year=1987 | volume=13 | pages=376-378 | url=http://adsabs.harvard.edu/abs/1987SvAL...13..376T | accessdate=2007-02-04 | | | }}</ref>。