论文标题
通过在银河磁盘运动学中的非对称性探索银河翘曲
Exploring the Galactic Warp Through Asymmetries in the Kinematics of the Galactic Disk
论文作者
论文摘要
先前对大型银河系恒星数据库的分析揭示了我们银河系的恒星磁盘被扭曲,并且这在太阳能邻里以外的恒星的运动学上赋予了强烈的签名。但是,由于准确距离估计的限制,许多尝试探索这些银河特征的程度的尝试通常仅限于太阳附近的体积。通过结合Gaia DR2天文溶液,Apogee调查中的星际距离和恒星丰度,我们介绍了银河磁盘中恒星的垂直和径向运动最详细且径向扩展的研究。我们绘制出恒星速度相对于它们的半乳突半径,角动量和方位角,并评估它们与扭曲的关系。在Galactic中心半径$ r = 13 \ \ text {kpc} $和角动量$ l_z = 2800 \ \ text {kpc} \\ text {km} {km} \ \ \ \ \ \ \ \ text {s}^{ - 1} $。在主要趋势上也发现了垂直和径向速度的较小涟漪。我们还发现,具有方位角垂直速度的趋势与峰并不对称,这表明经线会被斜视。为了解释垂直速度的全球趋势,我们建立了一个简单的银河经纱分析模型。我们的最佳拟合度的起始半径为$ 8.87^{+0.08} _ { - 0.09} \ \ \ \ text {kpc} $,预处理率为$ 13.57^{+0.20} _ { - 0.18} \ text {kpc}^{ - 1} $。这些参数在恒星年龄组之间保持一致,这一结果支持翘曲是外部,重力诱导现象的结果。
Previous analyses of large databases of Milky Way stars have revealed the stellar disk of our Galaxy to be warped and that this imparts a strong signature on the kinematics of stars beyond the solar neighborhood. However, due to the limitation of accurate distance estimates, many attempts to explore the extent of these Galactic features have generally been restricted to a volume near the Sun. By combining Gaia DR2 astrometric solution, StarHorse distance and stellar abundances from the APOGEE survey, we present the most detailed and radially expansive study yet of the vertical and radial motions of stars in the Galactic disk. We map stellar velocity with respect to their Galactocentric radius, angular momentum, and azimuthal angle and assess their relation to the warp. A decrease in vertical velocity is discovered at Galactocentric radius $R=13\ \text{kpc}$ and angular momentum $L_z=2800\ \text{kpc}\ \text{km}\ \text{s}^{-1}$. Smaller ripples in vertical and radial velocity are also discovered superposed on the main trend. We also discovered that trends in the vertical velocity with azimuthal angle are not symmetric about the peak, suggesting the warp to be lopsided. To explain the global trend in vertical velocity, we built a simple analytical model of the Galactic warp. Our best fit yields a starting radius of $8.87^{+0.08}_{-0.09}\ \text{kpc}$ and precession rate of $13.57^{+0.20}_{-0.18}\ \text{km}\ \text{s}^{-1}\ \text{kpc}^{-1}$. These parameters remain consistent across stellar age groups, a result that supports the notion that the warp is the result of an external, gravitationally induced phenomenon.