LAMOST J221750.59+210437.2: A new member of carbon-enhanced extremely metal-poor stars with excesses of Mg and Si
LAMOST J221750.59+210437.2: A new member of carbon-enhanced extremely metal-poor stars with excesses of Mg and Si
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LAMOST J221750.59 210437.2：镁和硅过量的碳增强极度贫金属恒星的新成员
DOI：
10.1093/pasj/psy092
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发表时间：
2018-07
影响因子：
2.3
通讯作者：
Kumar Y.B.
中科院分区：
文献类型：
--
作者：
Aoki W.;Matsuno T.;Honda S.;Ishigaki M.N.;Li H.N.;Suda T.;Kumar Y.B.
我们报告了我们与LAMOST和斯巴鲁进行的金属贫星调查发现的碳增强金属贫星（CEMP） J2217+2104的元素丰度。这颗天体是一颗红巨星，铁丰度极低（[Fe/H]=-4.0）， C、N和O含量显著增加，Na、Mg、Al和Si含量过量。这颗恒星是先前研究发现的一小群这样的CEMP恒星中的一个新例子。我们发现在这类物体中O-Zn的丰度模式非常相似，显示出元素到Si的增强和Ca和fe族元素的正常丰度。虽然这些恒星的C/N比率不同，但(C+N)/O比率是相似的。这表明C在祖细胞中也产生了与O-Zn相似的丰度比，并且后来受到了cn循环的影响。相比之下，J2217+2104中缺乏重中子捕获元素Sr和Ba，与之前研究的这类四种物体相比。这表明，早期星系中的中子捕获过程，可能是r过程，与形成这种CEMP恒星的现象没有直接联系。将这类CEMP恒星的丰度模式与超新星核合成模型的丰度模式进行比较，发现其祖恒星的质量约为25Msun，这与一般极贫金属恒星的典型祖恒星的质量没有特别的不同。
We report on the elemental abundances of the carbon-enhanced metal-poor (CEMP) star J2217+2104 discovered by our metal-poor star survey with LAMOST and Subaru. This object is a red giant having extremely low Fe abundance ([Fe/H]=-4.0) and very large enhancement of C, N, and O with excesses of Na, Mg, Al, and Si. This star is a new example of a small group of such CEMP stars identified by previous studies. We find a very similar abundance pattern for O-Zn in this class of objects that shows enhancement of elements up to Si and normal abundance of Ca and Fe-group elements. Whereas the C/N ratio is different among these stars, the (C+N)/O ratio is similar. This suggests that C was also yielded with similar abundance ratios relative to O-Zn in progenitors, and was later affected by the CN-cycle. By contrast, the heavy neutron-capture elements Sr and Ba are deficient in J2217+2104, compared to the four objects in this class previously studied. This indicates that the neutron-capture process in the early Galaxy, presumably the r-process, has no direct connection to the phenomenon that has formed such CEMP stars. Comparisons of the abundance pattern well determined for such CEMP stars with those of supernova nucleosynthesis models constrain the progenitor mass to be about 25Msun, which is not particularly different from typical mass of progenitors expected for extremely metal-poor stars in general.
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影响因子：
64.8
作者：
A. Frebel;W. Aoki;N. Christlieb;H. Ando;M. Asplund;P. Barklem;T. Beers;K. Eriksson;C. Fechner-C.-Fechne
通讯作者：
A. Frebel;W. Aoki;N. Christlieb;H. Ando;M. Asplund;P. Barklem;T. Beers;K. Eriksson;C. Fechner-C.-Fechne
DOI：
10.1086/422135
发表时间：
2004-02
期刊：
The Astrophysical Journal
影响因子：
--
作者：
T. Suda;M. Aikawa;M. Machida;M. Fujimoto;Icko Iben, Jr.,
通讯作者：
T. Suda;M. Aikawa;M. Machida;M. Fujimoto;Icko Iben, Jr.,
DOI：
10.1086/343761
发表时间：
2002-08
期刊：
The Astrophysical Journal Letters
影响因子：
--
作者：
W. Aoki;J. Norris;S. Ryan;T. Beers;H. Ando
通讯作者：
W. Aoki;J. Norris;S. Ryan;T. Beers;H. Ando
影响因子：
2.3
作者：
Takanori Nishimura;M. Aikawa;T. Suda;M. Fujimoto
通讯作者：
Takanori Nishimura;M. Aikawa;T. Suda;M. Fujimoto
DOI：
10.3847/0004-637x/833/1/21
发表时间：
2016-09
期刊：
The Astrophysical Journal
影响因子：
--
作者：
V. Placco;A. Frebel;T. Beers;Jinmi Yoon;A. Chiti;A. Heger;Conrad Chan;A. Casey;N. Christlieb
通讯作者：
V. Placco;A. Frebel;T. Beers;Jinmi Yoon;A. Chiti;A. Heger;Conrad Chan;A. Casey;N. Christlieb