反银心流和麒麟环的化学-动力学性质
Chemo-dynamical Nature of the Anticenter Stream and Monoceros Ring
AI总结：
本研究利用APOGEE巡天的高精度丰度对反银心流和麒麟环进行化学标记，发现其化学丰度与外薄盘外推值一致，排除矮星系起源，并暗示其与首次人马座矮球状星系经过有关。
摘要：
在深度测光巡天的时代，人们发现了大量的子结构，例如过密区和流。借助天体测量学和光谱学，在调查了它们的起源之后，学界揭示了银河系（MW）的复杂图景。离盘子结构反银心流（ACS）和麒麟环（MNC），曾被认为是正在瓦解的矮星系，后来发现它们与银河系外薄盘具有相似的运动学和金属丰度。在这项工作中，我们旨在利用APOGEE巡天的高精度丰度对ACS和MNC进行化学标记。通过外推外薄盘区域（10 < Rgc < 18 kpc，0 < |Zgc| < 3 kpc）的化学丰度趋势，我们发现ACS和MNC恒星在12种元素（包括C、N、O、Mg、Al、Si、K、Ca、Cr、Mn、Co和Ni）上的化学丰度与外推值一致。相似的化学模式表明ACS和MNC具有与银河系外薄盘相似的恒星形成历史，同时，我们也排除了它们与矮星系的关联，因为它们在多个化学空间中具有独特性。ACS和MNC恒星的年龄与首次人马座矮球状星系（Sgr dSph）经过的时间一致，表明它们之间可能存在联系。
英文摘要：
In the epoch of deep photometric surveys, a large number of substructures, e.g., over-densities, streams, were identified. With the help of astrometry and spectroscopy, the community revealed a complex picture of our Milky Way (MW) after investigating their origins. Off-plane substructures Anticenter Stream (ACS) and Monoceros Ring (MNC), once considered as dissolving dwarf galaxies, were later found to share similar kinematics and metallicity with the Galactic outer thin disk. In this work, we aim to chemically tag ACS and MNC with high-accuracy abundances from the APOGEE survey. By extrapolating chemical abundance trends in the outer thin disk region (10 < Rgc < 18 kpc, 0 < |Zgc| < 3kpc), we found that ACS and MNC stars show consistent chemical abundances as the extrapolating values for 12 elements, including C, N, O, Mg, Al, Si, K, Ca, Cr, Mn, Co and Ni. The similar chemical patterns indicate that ACS and MNC have similar star formation history as the MW outer thin disk, meanwhile, we also excluded their dwarf galaxy association, as they are distinctive in multiple chemical spaces. The ages of ACS and MNC stars are consistent with the time of the first Sgr dSph passage, indicating their possible connection.
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