论文标题
近距离和远处银河凸出恒星的金属性特性：Auriga模拟的期望
Metallicity Properties of the Galactic Bulge Stars Near and Far: Expectations from the Auriga Simulation
论文作者
论文摘要
使用Auriga模拟的高分辨率银河系模型，我们研究了银河凸起的化学性质，重点是近侧（银河中心前方）和远侧（银河系中心后方）的恒星之间的金属差。通常，沿着某些视线线比远端更富含金属，这与磁盘的负垂直金属梯度一致，因为远端位于磁盘平面上方高于近侧。但是，在该区域，在$ l <0^\ circ $和$ | b | \ le6^\ circ $，近侧比远端更具金属贫困，它们的差异随银河经度的变化而变化。这主要是由于杆的次要轴周围的恒星比主要轴周围的恒星更贫穷。由于钢筋被倾斜，在负经度区域，近侧主要由接近次轴区域的恒星比远端造成的，从而导致这种金属性差异。我们通过识别近边和远处的过度繁殖来提取X形结构中的恒星。它们的金属性特性与整个银河膨胀的结果一致。方形/花生形凸起可以自然解释观测中双红色团恒星的金属差异。无需涉及具有不同恒星种群的经典凸起组件。
Using the high resolution Milky Way-like model from Auriga simulation we study the chemical properties of the Galactic bulge, focusing on the metallicity difference between stars on the near side (in front of the Galactic center) and the far side (behind the Galactic center). In general, along certain sight lines the near side is more metal-rich than the far side, consistent with the negative vertical metallicity gradient of the disk, since the far side is located higher above the disk plane than the near side. However, at the region $l<0^\circ$ and $|b|\le6^\circ$, the near side is even more metal-poor than the far side, and their difference changes with the Galactic longitude. This is mainly due to the fact that stars around the minor axis of the bar are more metal-poor than those around the major axis. Since the bar is tilted, in the negative longitude region, the near side is mainly contributed by stars close to the minor axis region than the far side to result in such metallicity difference. We extract stars in the X-shape structure by identifying the overdensities in the near and far sides. Their metallicity properties are consistent with the results of the whole Galactic bulge. The boxy/peanut-shaped bulge can naturally explain the metallicity difference of the double red clump stars in observation. There is no need to involve a classical bulge component with different stellar populations.
