热亚矮星的研究进展
The Progress of hot Subdwarf Studies
查看参考文献102篇
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文摘
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热亚矮星以其独特的性质受到人们日益关注.它们是年老椭圆星系中良好的紫外源,系统地研究热亚矮星的观测特征和形成机制可以帮助我们理解恒星演化、椭圆星系中"紫外超"现象的起源和球状星团的动力学演化.热亚矮星的形成模型主要包括单星模型和双星模型.双星模型包含三种渠道:公共包层抛射渠道、稳定的洛希瓣物质交流渠道和双氦白矮星并合渠道.该文系统地总结了热亚矮星的观测特征,并简要介绍了它们的形成机制. |
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其他语种文摘
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Hot subdwarfs are exotic objects.They are core-helium-burning stars with very thin hydrogen-rich(or helium-rich)envelopes.Hot subdwarfs populate a very narrow area on the blueward extension of the horizontal branch(HB),the so called extreme/extended horizontal branch(EHB),in HR diagram.Their effective temperatures and logarithmic surface gravities are typically 20 000-80 000 K and 4.5-6.5 cgs,respectively.In general,three subgroups can be defined from photometric and spectroscopic classifications,i.e.subdwarf O(sdO),subdwarf OB (sdOB),subdwarf B(sdB).They have special atmospheric helium abundances.Hot subdwarfs radiate in ultraviolet(UV)and are believed to be responsible for the UV upturn of elliptical galaxies. Two scenarios for the formation of hot subdwarfs have been proposed,i.e.a single star model and a binary model.In the single star model,a star loses most of its envelope at the tip of the first giant branch and the remnant core is ignited to become a hot subdwarf.In the binary model, there are mainly three channels for the formation of hot subdwarfs,i.e.the common-envelope (CE)ejection channel for hot subdwarf binaries with short orbital periods;the stable Roche lobe overflow(RLOF)channel for hot subdwarf binaries with long orbital periods;the double helium white dwarf(WD)merger channel for single hot subdwarfs.Now,many hot subdwarfs are found in binaries(～2/3).The single star model is inconsistent with the latest observations of hot subdwarfs and the UV upturn of elliptical galaxies,while the binary model can explain the observations naturally. Systematic investigation of the formation and evolution of hot subdwarfs can help us to understand stellar evolution,the origin of the UV upturn of elliptical galaxies and the dynamical evolution of globular clusters. |
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来源
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天文学进展
,2008,26(2):126-138 【核心库】
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关键词
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天体物理学
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热亚矮星
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形成机制
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密近双星
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地址
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中国科学院, 云南, 昆明, 650011
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语种
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中文 |
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文献类型
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研究性论文 |
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ISSN
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1000-8349 |
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学科
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天文学 |
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基金
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国家自然科学基金
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文献收藏号
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CSCD:3314401
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