Chemical Abundances of New Member Stars in the Tucana II Dwarf Galaxy
Chemical Abundances of New Member Stars in the Tucana II Dwarf Galaxy
复制标题
图卡纳 II 矮星系新成员恒星的化学丰度
DOI：
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
J. Norris
中科院分区：
文献类型：
--
作者：
A. Chiti;A. Frebel;A. Ji;H. Jerjen;Dongwon Kim;J. Norris
基于6.5米麦哲伦-克莱望远镜上的MIKE摄谱仪获得的高分辨率光谱，我们给出了图卡纳II超暗矮星系（UFD）中7颗金属丰度从[Fe/H] =-3.3到[Fe/H] =-2.4的恒星的化学丰度测量结果。对于三颗恒星，我们首次提供了详细的化学丰度。其中两颗恒星是新发现的杜鹃座II的成员，并从SkyMapper望远镜拍摄的杜鹃座II UFD的深窄带测光中被选为可能的成员。这一结果表明，光度识别矮星系系统的化学成分的基础上的成员的潜力。从步行者等人的成员星表中选出了一颗新的星星。在我们的样本中的其他四颗恒星在进行额外的观测后进行了重新分析。总体而言，六颗恒星的化学丰度是UFD恒星群的特征。第七颗星星的化学丰度与其他杜鹃座II成员不同，并且具有非典型的、比典型UFD恒星预期的更高的锶丰度。虽然不太可能，但它的锶丰度增加了它可能是一颗前景贫金属晕星星的可能性，其系统速度与Tucana II相同。如果我们把这颗星星排除在外，图卡纳二号将满足成为幸存的第一个星系的标准。否则，这颗星星意味着杜鹃座II可能经历了某种程度的化学演化。
We present chemical abundance measurements for seven stars with metallicities ranging from Fe/H] = −3.3 to [Fe/H] = −2.4 in the Tucana II ultra-faint dwarf galaxy (UFD), based on high-resolution spectra obtained with the MIKE spectrograph on the 6.5 m Magellan-Clay Telescope. For three stars, we present detailed chemical abundances for the first time. Of those, two stars are newly discovered members of Tucana II and were selected as probable members from deep narrowband photometry of the Tucana II UFD taken with the SkyMapper telescope. This result demonstrates the potential for photometrically identifying members of dwarf galaxy systems based on chemical composition. One new star was selected from the membership catalog of Walker et al. The other four stars in our sample have been reanalyzed, following additional observations. Overall, six stars have chemical abundances that are characteristic of the UFD stellar population. The seventh star shows chemical abundances that are discrepant from the other Tucana II members and an atypical, higher strontium abundance than what is expected for typical UFD stars. While unlikely, its strontium abundance raises the possibility that it may be a foreground metal-poor halo star with the same systemic velocity as Tucana II. If we were to exclude this star, Tucana II would satisfy the criteria to be a surviving first galaxy. Otherwise, this star implies that Tucana II has likely experienced somewhat extended chemical evolution.
DOI：
10.1086/590336
发表时间：
2008-05
期刊：
The Astrophysical Journal
影响因子：
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作者：
N. Martin;J. D. de Jong;H. Rix
通讯作者：
N. Martin;J. D. de Jong;H. Rix
影响因子：
6.5
作者：
Feltzing;Matteucci
通讯作者：
Matteucci