DETAILED ABUNDANCES OF TWO VERY METAL-POOR STARS IN DWARF GALAXIES
DETAILED ABUNDANCES OF TWO VERY METAL-POOR STARS IN DWARF GALAXIES
复制标题
矮星系中两颗金属非常贫乏的恒星的详细丰度
DOI：
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
J. Cohen
中科院分区：
文献类型：
--
作者：
E. Kirby;J. Cohen
在矮球状星系（dSphs）中，大多数贫金属恒星可以显示出一个或几个超新星（SNe）的核合成模式。这些SNe的金属丰度可能为零，使得贫金属的dSph星成为最接近星族III的恒星。贫金属dSph星也有助于揭示银河系晕的形成机制。我们提出了详细的丰度从凯克/HIRES光谱两个非常贫金属恒星在两个MW dSphs。其中一颗星星位于玉夫座dSph，[Fe i/H] =-2.40。另一颗星星位于小熊座dSpha，[Fe i/H] =-3.16。这两颗恒星都落在先前发现的低金属量，高[α/Fe]平台上。在这两个dSphs中，大多数贫金属恒星的丰度比与贫金属晕星基本一致。然而，钠和一些r-过程元素的丰度位于类似金属丰度的内晕星所定义的包络线的下端。我们认为SN产率的金属丰度依赖性是原因。低质量dSphs中最早的SNe比大质量晕祖星中最早的SNe有更少的气体污染。因此，dSph星在−3 < [Fe/H] < −2时的样本SNe为[Fe/H]<$−3，而晕星在相同金属丰度范围内的样本SNe为[Fe/H]<$−3。因此，[Na/Fe]和[r/Fe]的增强被推迟到更高的金属丰度dSphs比内晕的祖先。
The most metal-poor stars in dwarf spheroidal galaxies (dSphs) can show the nucleosynthetic patterns of one or a few supernovae (SNe). These SNe could have zero metallicity, making metal-poor dSph stars the closest surviving links to Population III stars. Metal-poor dSph stars also help to reveal the formation mechanism of the Milky Way (MW) halo. We present the detailed abundances from Keck/HIRES spectroscopy for two very metal-poor stars in two MW dSphs. One star, in the Sculptor dSph, has [Fe i/H] = -2.40. The other star, in the Ursa Minor dSph, has [Fe i/H] = -3.16. Both stars fall in the previously discovered low-metallicity, high-[α/Fe] plateau. Most abundance ratios of very metal-poor stars in these two dSphs are largely consistent with very metal-poor halo stars. However, the abundances of Na and some r-process elements lie at the lower end of the envelope defined by inner halo stars of similar metallicity. We propose that the metallicity dependence of SN yields is the cause. The earliest SNe in low-mass dSphs have less gas to pollute than the earliest SNe in massive halo progenitors. As a result, dSph stars at −3 < [Fe/H] < −2 sample SNe with [Fe/H] ≪ −3, whereas halo stars in the same metallicity range sample SNe with [Fe/H] ∼ −3. Consequently, enhancements in [Na/Fe] and [r/Fe] were deferred to higher metallicity in dSphs than in the progenitors of the inner halo.
影响因子：
6.5
作者：
Wolfgang Hayek;Wolfgang Hayek;U. Wiesendahl;N. Christlieb;Kjell Eriksson;A. Korn;P. Barklem;
通讯作者：
Wolfgang Hayek;Wolfgang Hayek;U. Wiesendahl;N. Christlieb;Kjell Eriksson;A. Korn;P. Barklem;
DOI：
10.1086/508878
发表时间：
2006-09
期刊：
The Astrophysical Journal Letters
影响因子：
--
作者：
W. Aoki;S. Bisterzo;R. Gallino;T. Beers;J. Norris;S. Ryan;S. Tsangarides
通讯作者：
W. Aoki;S. Bisterzo;R. Gallino;T. Beers;J. Norris;S. Ryan;S. Tsangarides