A GALAH view of the chemical homogeneity and ages of stellar strings identified in Gaia
A GALAH view of the chemical homogeneity and ages of stellar strings identified in Gaia
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盖亚中发现的恒星弦的化学均匀性和年龄的 GALAH 视图
DOI：
10.1093/mnras/stac236
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发表时间：
2022
影响因子：
4.8
通讯作者：
Maas, Zachary G.
中科院分区：
文献类型：
--
作者：
Manea, Catherine;Hawkins, Keith;Maas, Zachary G.
盖亚的出现导致了近300个细长的恒星协会（称为“弦”）的发现，长度跨越数百秒差距，宽度只有几十秒差距。这些新发现的种群为研究银河系薄盘的组装过程提供了一个很好的实验室。在这项工作中，我们使用来自GALAH DR 3的数据来研究18个新发现的恒星种群的化学分布和年龄，其中10个是弦，其中8个是紧凑的形态。我们估计的内在丰度分散在[X/H]的每个人口，并比较他们的本地领域和疏散星团（OC）M 67。我们发现，所有这些群体，但一个更化学均匀比他们的本地领域。此外，有一半的弦，即Theias 139，169，216，303和309，在大多数元素中具有范围在0.01和0.07 dex之间的固有[X/H]色散，相当于许多OC的色散。这些结果提供了重要的新的观测约束星星的形成和化学均匀性的本地星际介质（ISM）。我们调查了每个种群的锂和化学钟丰度（例如[Sc/Ba]，[Ca/Ba]，[Ti/Ba]和[Mg/Y]），并发现化学建议的年龄通常支持除6个结构外的所有结构的等时年龄。这项工作突出了化学在研究运动学相关恒星群中的独特优势。
The advent ofGaiahas led to the discovery of nearly 300 elongated stellar associations (called ‘strings’) spanning hundreds of parsecs in length and mere tens of parsecs in width. These newfound populations present an excellent laboratory for studying the assembly process of the Milky Way thin disc. In this work, we use data from GALAH DR3 to investigate the chemical distributions and ages of 18 newfound stellar populations, 10 of which are strings and 8 of which are compact in morphology. We estimate the intrinsic abundance dispersions in [X/H] of each population and compare them with those of both their local fields and the open cluster (OC) M 67. We find that all but one of these groups are more chemically homogeneous than their local fields. Furthermore, half of the strings, namely Theias 139, 169, 216, 303, and 309, have intrinsic [X/H] dispersions that range between 0.01 and 0.07 dex in most elements, equivalent to those of many OCs. These results provide important new observational constraints on star formation and the chemical homogeneity of the local interstellar medium (ISM). We investigate each population’s Li and chemical clock abundances (e.g. [Sc/Ba], [Ca/Ba], [Ti/Ba], and [Mg/Y]) and find that the ages suggested by chemistry generally support the isochronal ages in all but six structures. This work highlights the unique advantages that chemistry holds in the study of kinematically related stellar groups.