Evidence of a Metal-rich Galactic Bar from the Vertex Deviation of the Velocity Ellipsoid
Evidence of a Metal-rich Galactic Bar from the Vertex Deviation of the Velocity Ellipsoid
复制标题
DOI：
10.1086/521098
复制
发表时间：
2006-11
期刊：
影响因子：
--
通讯作者：
M. Soto;R. Rich;K. Kuijken
中科院分区：
文献类型：
--
作者：
M. Soto;R. Rich;K. Kuijken
在Baade窗(L，b)=(0.9°，-4°)银河系凸起场中，我们综合了315K和M巨星的径向速度、自行和低分辨丰度。具有[Fe/H]>；-0.5Dex的恒星的速度椭球在径向速度与横向速度的曲线图上显示出顶点偏差，这与轨道支持条的恒星群的预期一致。我们证明，使用非参数等级相关统计量，这种顶点偏差的重要性是>；99%。贫金属([Feh]<；-0.5)群的速度椭球没有顶点偏离，与各向同性的扁平旋转群相一致。我们没有发现运动学亚群的证据，但垂直速度弥散σb有随金属丰度增加而减小的温和趋势。
We combine radial velocities, proper motions, and low-resolution abundances for a sample of 315 K and M giants in the Baade's window (l, b) = (0.9°, -4°) Galactic bulge field. The velocity ellipsoid of stars with [Fe/H] > -0.5 dex shows a vertex deviation in the plot of radial versus transverse velocity, consistent with that expected from a population with orbits supporting a bar. We demonstrate that the significance of this vertex deviation, using nonparametric rank correlation statistic, is >99%. The velocity ellipsoid for the metal-poor ([FeH] < -0.5) part of the population shows no vertex deviation and is consistent with an isotropic, oblate rotating population. We find no evidence of kinematic subgroups, but there is a mild tendency for the vertical velocity dispersion σb to decrease with increasing metallicity.