Milky Way运动：第四象限次中心点的测量
Milky Way Kinematics: Measurements at the Subcentral Point of the Fourth Quadrant
摘要：
我们使用原子氢（HI）的数据从南银河系平面调查，研究银河系的第四象限的运动学。通过测量银河系第四象限内作为经度函数的终极速度，我们得出了银河系在3 < R < 8 kpc之间采样最密集的旋转曲线。我们确定了一个新的关节旋转曲线适合的第一和第四象限，它可以用于运动学距离内部的太阳圆。根据我们的数据，我们将第四象限中的流运动的峰到峰变化的新限制为~10 km/s。我们发现，在终极速度以外的平均HI轮廓的形状是一致的气体的三个速度色散，冷组件与$Δv=6.3$公里/秒，温暖的组件与$Δv=12.3$公里/秒和快速组件与$Δv=25.9$公里/秒。检查宽度与银河系半径，我们发现，最西端的两个组件显示出很小的变化与半径和它们的小尺度波动跟踪对方非常好，这表明它们共享相同的云到云的运动。最宽分量的宽度在R<4 kpc之前是恒定的，在R<4 kpc时，宽度急剧增加。
英文摘要：
We use atomic hydrogen (HI) data from the Southern Galactic Plane Survey to study the kinematics of the fourth quadrant of the Milky Way. By measuring the terminal velocity as a function of longitude throughout the fourth Galactic quadrant we have derived the most densely sampled rotation curve available for the Milky Way between 3 < R < 8 kpc. We determine a new joint rotation curve fit for the first and fourth quadrants, which can be used for kinematic distances interior to the Solar circle. From our data we place new limits on the peak to peak variation of streaming motions in the fourth quadrant to be ~10 km/s. We show that the shape of the average HI profile beyond the terminal velocity is consistent with gas of three velocity dispersions, a cold component with $Δv=6.3$ km/s, a warmer component with $Δv=12.3$ km/s and a fast component with $Δv=25.9$ km/s. Examining the widths with Galactic radius we find that the narrowest two components show little variation with radius and their small scale fluctuations track each other very well, suggesting that they share the same cloud-to-cloud motions. The width of the widest component is constant until R<4 kpc, where it increases sharply.
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