论文标题
Gjöll流与NGC 3201之间的化学动力联系
A chemo-dynamical link between the Gjöll stream and NGC 3201
论文作者
论文摘要
最近对Gaia的第二个数据发布的分析显示，银河系周围有许多新的恒星流。有人提出，这些流之一Gjöll与球形群集NGC 3201有关，但到目前为止，该关联仅基于流星的运动学。在这项工作中，我们确定了Gaia数据中的五个可能的流构件，它们足够明亮，可以通过麦当劳天文台的Harlan J. Smith望远镜进行高分辨率光谱的随访。一颗恒星根据其径向速度被排除在成员中。对剩余四个运动学成员的丰度分析表明，两个恒星与NGC 3201的化学匹配良好，这是由它们相似的Al和$α$元素丰度驱动的。在其余两个中，一个没有与NGC 3201的化学相似性，并且可能是无关的银河系恒星，而另一个则表现出类似的Al丰度，但具有较低的$α$元素丰度。 Gjöll流到NGC 3201中恒星的化学标记证实了这一关联，并提供了银河系的分层形成的直接证明。
Recent analysis of the second data release of Gaia has revealed a number of new stellar streams surrounding the Milky Way. It has been suggested that one of these streams, Gjöll, is associated with the globular cluster NGC 3201, but thus far the association has only been based on kinematics of the stream stars. In this work we identify five likely stream members in the Gaia data that are bright enough for high-resolution spectroscopic follow-up with the Harlan J. Smith telescope at McDonald Observatory. One star is ruled out as a member based on its radial velocity. Abundance analysis of the remaining four kinematic members reveals a good chemical match to NGC 3201 for two of the stars, driven by their similar Al and $α$-element abundances. Of the remaining two, one shows no chemical similarity to NGC 3201 and is likely an unassociated Milky Way halo field star, while the other exhibits a similar Al abundance but has somewhat lower $α$-element abundances. The chemical tagging of stars in the Gjöll stream to NGC 3201 confirms this association and provides direct proof of the hierarchical formation of the Milky Way.
