The chemical evolution of the dwarf spheroidal galaxy Sextans
The chemical evolution of the dwarf spheroidal galaxy Sextans
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矮椭球星系 Sextans 的化学演化
DOI：
10.1051/0004-6361/201937146
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发表时间：
2020
影响因子：
6.5
通讯作者：
Theler R
中科院分区：
文献类型：
--
作者：
Theler R
我们提出了我们的分析的FLAMES数据集，针对中央25 '区域的六分仪矮球状星系（dSph）。该数据集是矮星系丰度和径向速度小组获得的ESO大型计划171.B-0588（A）的高分辨率光谱部分的第三个主要部分。我们的样本是由红巨星分支恒星组成的，低至V 20.5等，六分仪中水平分支的水平，并允许用户解决与恒星核合成和星系演化相关的问题。 我们提供了81颗恒星的金属丰度，涵盖了[Fe/H] = −3.2到−1.5 dex的范围。其他10种元素的丰度是：Mg，Ca，Ti，Sc，Cr，Mn，Co，Ni，Ba和Eu。尽管质量很小，六分仪是一个化学演化的系统，有证据表明核心坍缩和Ia型超新星以及低金属丰度的渐近巨星分支星（AGB）的贡献。这个新的FLAMES样本提供了足够多的恒星，其化学丰度以高精度导出，以牢固地建立[α/Fe]在<$0.4 dex处的平台的存在，然后下降到[Fe/H]<$−2 dex以上。尽管天炉座和玉夫座的质量和星星形成历史非常不同，但这些特征揭示了它们与天炉座和玉夫座dSphs的密切相似性，这表明这三个星系在早期形成阶段具有非常相似的星星形成效率，可能是由早期较小星系碎片的吸积驱动的，直到紫外线背景加热以不同的方式影响它们。当考虑Ba和Eu时，Sculptor和六分仪dSph之间的相似性也是惊人的。在两个星系共同的金属丰度区域中可以看到相同的化学趋势，这意味着SNeIa和低金属丰度AGB的比例相似。最后，对于铁峰元素，[Co/Fe]和[Ni/Fe]在[Fe/H]<$−2以上的下降意味着在SNeIa中Ni和Co的产率低于Fe。[Ni/Fe]的减少有利于基于双简并亚亚rasekhar质量白色矮星爆炸的SNeIa模型。
We present our analysis of the FLAMES dataset targeting the central 25′ region of the Sextans dwarf spheroidal galaxy (dSph). This dataset is the third major part of the high-resolution spectroscopic section of the ESO large program 171.B-0588(A) obtained by the Dwarf galaxy Abundances and Radial-velocities Team. Our sample is composed of red giant branch stars down toV∼ 20.5 mag, the level of the horizontal branch in Sextans, and allows users to address questions related to both stellar nucleosynthesis and galaxy evolution. We provide metallicities for 81 stars, which cover the wide [Fe/H] = −3.2 to −1.5 dex range. The abundances of ten other elements are derived: Mg, Ca, Ti, Sc, Cr, Mn, Co, Ni, Ba, and Eu. Despite its small mass, Sextans is a chemically evolved system, showing evidence of a contribution from core-collapse and Type Ia supernovae as well as low-metallicity asymptotic giant branch stars (AGBs). This new FLAMES sample offers a sufficiently large number of stars with chemical abundances derived with high accuracy to firmly establish the existence of a plateau in [α/Fe] at ∼0.4 dex followed by a decrease above [Fe/H] ∼ −2 dex. These features reveal a close similarity with the Fornax and Sculptor dSphs despite their very different masses and star formation histories, suggesting that these three galaxies had very similar star formation efficiencies in their early formation phases, probably driven by the early accretion of smaller galactic fragments, until the UV-background heating impacted them in different ways. The parallel between the Sculptor and Sextans dSph is also striking when considering Ba and Eu. The same chemical trends can be seen in the metallicity region common to both galaxies, implying similar fractions of SNeIa and low-metallicity AGBs. Finally, as to the iron-peak elements, the decline of [Co/Fe] and [Ni/Fe] above [Fe/H] ∼ −2 implies that the production yields of Ni and Co in SNeIa are lower than that of Fe. The decrease in [Ni/Fe] favours models of SNeIa based on the explosion of double-degenerate sub-Chandrasekhar mass white dwarfs.
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球状星团和矮星系中铬、钴和镍丰度目录
DOI：
10.3847/1538-4365/aac952
发表时间：
2018
期刊：
The Astrophysical Journal Supplement Series
影响因子：
--
作者：
E. Kirby;Justin L. Xie;Rachel Guo;M. Kovalev;M. Bergemann
通讯作者：
M. Bergemann
DOI：
10.3847/1538-4365/aa755e
发表时间：
2017
期刊：
The Astrophysical Journal Supplement Series
影响因子：
--
作者：
J. Norris;D. Yong;K. Venn;G. Gilmore;L. Casagrande;A. Dotter
通讯作者：
A. Dotter
追踪低表面亮度银河系矮星系的恒星成分到其郊区
影响因子：
6.5
作者：
L. Cicuéndez;G. Battaglia;M. Irwin;J. Bermejo;B. McMonigal;N. Bate;G. Lewis;A. Conn;T. D. Boer;C. Gallart;M. Guglielmo;R. Ibata;A. McConnachie;E. Tolstoy;N. Fernando
通讯作者：
N. Fernando
DOI：
10.1146/annurev-astro-091918-104453
发表时间：
2019-01
影响因子：
33.3
作者：
J. Simon
通讯作者：
J. Simon
DOI：
10.1086/323407
发表时间：
2001-12
期刊：
The Astrophysical Journal
影响因子：
--
作者：
J. Lawler;M. Wickliffe;E. A. Hartog;C. Sneden
通讯作者：
J. Lawler;M. Wickliffe;E. A. Hartog;C. Sneden