论文标题
洞悉银河系磁盘系统的形成和进化历史
Insights into the Formation and Evolution History of the Galactic Disk System
论文作者
论文摘要
我们对银河磁盘中的23,908 G-和K型矮人的样品进行了运动分析。根据$α$ - 充足的比率，[$α$/fe]，我们将样品分为低$ $ $α$薄盘和高$α$厚的盘星。我们找到$ v _ {\ rm ϕ} $ $ - $ - $ - $ 28.2 km s $^{ - 1} $ dex $^{ - 1} $ for Thin Disk的[Fe/H]，以及$ v _ {\ rm r} $，$ V _ $ v _的速度分散的速度几乎平坦的趋势$ v _ {\ rm z} $组件，带有[fe/h]。 The metal-poor (MP; [Fe/H] $<$ $-$0.3) thin-disk stars with low-$V_{\rm ϕ}$ velocities have high eccentricities ($e$) and small perigalacticon distances ($r_{\rm p}$), while the high-$V_{\rm ϕ}$ MP thin-disk stars possess low $e$ and大$ r _ {\ rm p} $。有趣的是，薄磁盘中的超级金属丰富（[Fe/h] $> $+$ 0.1）的一半星是低$ e $，类似太阳能轨道的一半。考虑到具有各种运动学的薄盘恒星的不均匀金属性分布需要通过搅拌$ - $来影响径向迁移 - 显然会强烈影响薄磁盘的当前结构；我们不能排除模糊高级星的重要性。我们得出了$+$+$ 36.9 km s $^{ - 1} $ dex $^{ - 1} $的旋转速度梯度，较厚磁盘$降低了速度分散的趋势，随着[Fe/H]的增加。厚盘人的偏心率也广泛分布，高$ e $ $星的数量随着[Fe/h]的减少而增加。这些运动学行为可能是暴力机制的结果，例如气体丰富的合并或巨型湍流团的存在，在其形成的历史早期。小次合并和径向迁移的动态加热也可能在形成当前的厚盘结构中起作用。
We present a kinematic analysis of a sample of 23,908 G- and K-type dwarfs in the Galactic disk. Based on the $α$-abundance ratio, [$α$/Fe], we separated our sample into low-$α$ thin-disk and high-$α$ thick-disk stars. We find a $V_{\rm ϕ}$ gradient of $-$28.2 km s$^{-1}$ dex$^{-1}$ over [Fe/H] for the thin disk, and an almost flat trend of the velocity dispersions of $V_{\rm R}$, $V_{\rm ϕ}$, and $V_{\rm Z}$ components with [Fe/H]. The metal-poor (MP; [Fe/H] $<$ $-$0.3) thin-disk stars with low-$V_{\rm ϕ}$ velocities have high eccentricities ($e$) and small perigalacticon distances ($r_{\rm p}$), while the high-$V_{\rm ϕ}$ MP thin-disk stars possess low $e$ and large $r_{\rm p}$. Interestingly, half of the super metal-rich ([Fe/H] $>$ $+$0.1) stars in the thin disk exhibit low-$e$, solar-like orbits. Accounting for the inhomogeneous metallicity distribution of the thin-disk stars with various kinematics requires radial migration by churning $-$ it apparently strongly influences the current structure of the thin disk; we cannot rule out the importance of blurring for the high-$e$ stars. We derive a rotation velocity gradient of $+$36.9 km s$^{-1}$ dex$^{-1}$ for the thick disk, and decreasing trends of velocity dispersions with increasing [Fe/H]. The thick-disk population also has a broad distribution of eccentricity, and the number of high-$e$ stars increases with decreasing [Fe/H]. These kinematic behaviors could be the result of a violent mechanism, such as a gas-rich merger or the presence of giant turbulent clumps, early in the history of its formation. Dynamical heating by minor mergers and radial migration may also play roles in forming the current thick-disk structure.
