标题： 银河系中金属含量较低的恒星盘隐藏在盖亚-萨乌萨奇-恩克拉多斯碎片中：APOGEE DR17视角 显示英文标题

标题： The metal-weak Milky Way stellar disk hidden in the Gaia-Sausage-Enceladus debris: the APOGEE DR17 view

摘要： 我们首次通过结合元素丰度和运动学特征，识别了银河系中的早期恒星盘。 使用来自APOGEE DR17和Gaia的数据，我们在Mg-Mn-Al-Fe平面上选择具有吸积起源特征的元素丰度的恒星，并发现具有晕状运动学和盘状运动学的恒星。 具有晕状运动学的恒星位于[Mg/Fe]较低的序列上，而具有盘状运动学的恒星位于较高的序列上。 通过地震学观测，我们确定具有晕状运动学的恒星年龄较大，为9-11 Gyr，而更演化的恒星盘大约年轻1-2 Gyr。 我们表明，位于深绑定轨道上的恒星的原位比例并不小，实际上，银河系内部很可能同时包含真正的原位恒星群体和吸积恒星群体。 此外，我们在En-Lz平面上对Gaia-Sausage-Enceladus的选取并不是非常稳健。 事实上，截然不同的选取标准对于吸积恒星给出了几乎相同的元素丰度特征。 显示英文摘要

摘要： We have for the first time identified the early stellar disk in the Milky Way by using a combination of elemental abundances and kinematics. Using data from APOGEE DR17 and Gaia we select stars in the Mg-Mn-Al-Fe plane with elemental abundances indicative of accreted origin and find stars with both halo-like and disk-like kinematics. The stars with halo-like kinematics lie along a lower sequence in [Mg/Fe], while the stars with disk-like kinematics lie along a higher sequence. Through with asteroseismic observations, we determine the stars with halo-like kinematics are old, 9-11 Gyr and that the more evolved stellar disk is about 1-2 Gyr younger. We show that the in situ fraction of stars on deeply bound orbits is not small, in fact the inner Galaxy likely harbours a genuine in-situ population together with an accreted one. In addition, we show that the selection of Gaia-Sausage-Enceladus in the En-Lz plane is not very robust. In fact, radically different selection criteria give almost identical elemental abundance signatures for the accreted stars.