Galactic Kinematics toward the South Galactic Pole: First Results from the Yale-San Juan Southern Proper Motion Program
Galactic Kinematics toward the South Galactic Pole: First Results from the Yale-San Juan Southern Proper Motion Program
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DOI：
10.1086/301198
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发表时间：
1991-03
期刊：
影响因子：
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通讯作者：
R. Mendez;I. Platais;T. Girard;V. Kozhurina-Platais;W. V. van Altena
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文献类型：
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作者：
R. Mendez;I. Platais;T. Girard;V. Kozhurina-Platais;W. V. van Altena
将银河系结构和运动学模型代码的预测与南方自行调查得出的颜色计数和绝对自行进行比较，覆盖了9 < BJ ≤ 19范围内朝向银河系南极超过700 ° 2的区域。的理论假设和相关的计算程序，几何的运动学模型，并通过参数的详细介绍，并与其他同类的银河系运动学模型进行比较。与该模型进行比较的数据由30，000多颗随机选择的恒星组成，它们最适合的模型是V分量（指向银河系旋转方向）中太阳特有运动为+5 km s-1，LSR速度为270 km s-1，并且（盘）速度椭球始终指向银河系中心。U分量中的绝对自行表明太阳的特有运动为11.0 ± 1.5 km s-1，不需要局部膨胀或收缩项。微弱的绝对运动表明，厚盘必须表现出相当陡峭的速度梯度约为-36 km s-1 kpc-1的LSR。我们无法对晕的整体旋转或厚盘或晕速度分散设置约束。U和V自行中的一些子结构可能存在于较亮的仓中，10 < BJ < 13，它可能指示（磁盘）移动的群体。
The predictions from a Galactic structure and kinematic model code are compared with the color counts and absolute proper motions derived from the Southern Proper Motion survey, covering more than 700 deg2 toward the south Galactic pole in the range 9 < BJ ≤ 19. The theoretical assumptions and associated computational procedures, the geometry for the kinematic model, and the adopted parameters are presented in detail and compared with other Galactic kinematic models of its kind. The data with which the model is compared consist of more than 30,000 randomly selected stars, and they are best fitted by models with a solar peculiar motion of +5 km s-1 in the V-component (pointing in the direction of Galactic rotation), a high LSR speed of 270 km s-1, and a (disk) velocity ellipsoid that always points toward the Galactic center. The absolute proper motions in the U-component indicate a solar peculiar motion of 11.0 ± 1.5 km s-1, with no need for a local expansion or contraction term. The fainter absolute motions show an indication that the thick disk must exhibit a rather steep velocity gradient of about -36 km s-1 kpc-1 with respect to the LSR. We are not able to set constraints on the overall rotation for the halo or on the thick disk or halo velocity dispersions. Some substructure in the U and V proper motions could be present in the brighter bins, 10 < BJ < 13, and it might be indicative of (disk) moving groups.