The formation of the Milky Way halo and its dwarf satellites; a NLTE-1D abundance analysis
The formation of the Milky Way halo and its dwarf satellites; a NLTE-1D abundance analysis
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DOI：
10.1051/0004-6361/201730779
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发表时间：
2017-04
影响因子：
6.5
通讯作者：
L. Mashonkina;P. Jablonka;P. Jablonka;Y. Pakhomov;T. Sitnova;P. North
中科院分区：
文献类型：
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作者：
L. Mashonkina;P. Jablonka;P. Jablonka;Y. Pakhomov;T. Sitnova;P. North
我们为矮球状星系（dSphs）雕刻家星系、小熊座星系、六分星星系、天炉星系、双星星系I、大熊座星系II和狮子座IV的非常和极端金属贫乏恒星的完整样本提供了一套均匀的精确大气参数。我们还提供了一个银河系（MW）的巨星比较样本，涵盖了4:3:5的制度，Tii/Tiii电离平衡在NLTE计算中得到满足。在logt -eff平面上，所有的恒星都位于进化轨迹的巨大分支上，对应于[Fe /H] = 2到4，与它们的金属丰度一致。对于我们样本中一些最缺乏金属的恒星，我们从铁和钛的两个电离阶段获得了相对不一致的NLTE丰度。我们认为这是这些金属丰度的t - efft - color关系的不确定性的结果。这项工作的结果为在一篇论文中提出的详细丰度分析提供了基础。
We present a homogeneous set of accurate atmospheric parameters for a complete sample of very and extremely metal-poor stars in the dwarf spheroidal galaxies (dSphs) Sculptor, Ursa Minor, Sextans, Fornax, Botes I, Ursa Major II, and Leo IV. We also deliver a Milky Way (MW) comparison sample of giant stars covering the 4 3 : 5 regime, the Tii/Tiii ionisation equilibrium is fulfilled in the NLTE calculations. In the logg T-eff plane, all the stars sit on the giant branch of the evolutionary tracks corresponding to [Fe /H] = 2 to 4, in line with their metallicities. For some of the most metal-poor stars of our sample, we achieve relatively inconsistent NLTE abundances from the two ionisation stages for both iron and titanium. We suggest that this is a consequence of the uncertainty in the T-eff-colour relation at those metallicities. The results of this work provide the basis for a detailed abundance analysis presented in a companion paper.