论文标题
在超淡矮星系的郊区为成员寻找宇宙的狩猎：Ursa Major I，Coma Berenices和BoötesI
The Cosmic Hunt for Members in the Outskirts of Ultra Faint Dwarf Galaxies: Ursa Major I, Coma Berenices, and Boötes I
论文作者
论文摘要
GAIA EDR3数据用于识别三个超弱矮人（UFD）星系的郊区的潜在成员； COMA BERENICE（> 2RH），URSA专业I（$ \ sim $ 4RH）和BoötesI（$ \ sim $ 4RH），以及Ursa Major I的新成员I。这些目标是通过Gemini Gracs光谱仪观察到的，这些目标是用来确定精确的辐射速度和Metallicition successuitiation successuitiation spectograph。光谱还用于测量10个元素（Na，Mg，K，Ca，Sc，Ti，Cr，Fe，Fe，Ni和Ba）的吸收线，这些元素证实了最外面恒星的化学丰度与中央区域的恒星非常吻合。昏迷中恒星的丰度比和化学模式与SN IA的贡献是一致的，SN IA的贡献是不寻常的，因为其恒星形成史，与以前的建议相抵触，即该系统从单个核心崩溃的超新星事件中化学演变。这三个星系的化学分布与中央区域中最外面的恒星一致，然后通过潮汐剥离和/或超新星反馈移动到当前位置。然而，在博特斯一世中，其最外面恒星的较低金属性和缺乏较强的碳富集也可能是矮星系合并的证据。
Gaia EDR3 data was used to identify potential members in the outskirts of three ultra faint dwarf (UFD) galaxies; Coma Berenices (> 2Rh), Ursa Major I ($\sim$ 4Rh), and Boötes I ($\sim$ 4Rh), as well as a new member in the central region of Ursa Major I. These targets were observed with the Gemini GRACES spectrograph, which was used to determine precision radial velocities and metallicities that confirm their associations with the UFD galaxies. The spectra were also used to measure absorption lines for 10 elements (Na, Mg, K, Ca, Sc, Ti, Cr, Fe, Ni, and Ba), which confirm that the chemical abundances of the outermost stars are in good agreement with stars in the central regions. The abundance ratios and chemical patterns of the stars in Coma Berenices are consistent with contributions from SN Ia, which is unusual for its star formation history and in conflict with previous suggestions that this system evolved chemically from a single core collapse supernova event. The chemistries for all three galaxies are consistent with the outermost stars forming in the central regions, then moving to their current locations through tidal stripping and/or supernova feedback. In Boötes I, however, the lower metallicity and lack of strong carbon enrichment of its outermost stars could also be evidence of a dwarf galaxy merger.
