The 3D Galactocentric Velocities of Kepler Stars: Marginalizing Over Missing Radial Velocities
The 3D Galactocentric Velocities of Kepler Stars: Marginalizing Over Missing Radial Velocities
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DOI：
10.3847/1538-3881/ac6fea
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发表时间：
2022-05
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影响因子：
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通讯作者：
R. Angus;A. Price-Whelan;J. Zinn;M. Bedell;Y. Lu;D. Foreman-Mackey
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作者：
R. Angus;A. Price-Whelan;J. Zinn;M. Bedell;Y. Lu;D. Foreman-Mackey
精确的盖亚位置测量，松弛，和自行提供了一个机会来计算3D位置和2D速度（即，5D相空间）的银河系恒星。光谱径向速度（RV）测量提供了完整的6D相空间信息，但是现在和将来仍然有许多恒星没有RV测量。如果没有RV，就不可能直接计算3D恒星速度;然而，人们可以通过边缘化缺失的RV维度来推断3D恒星速度。本文推导了笛卡尔银心坐标系（vx，vy，vz）下开普勒场中恒星的三维速度。我们直接计算速度约四分之一的开普勒目标，使用RV测量可从盖亚，LAMOST和APOGEE光谱调查。使用这些恒星的速度分布作为我们的先验知识，我们通过在RV维度上边缘化来推断剩余四分之三样本的速度。我们推断的v x、v y和v z速度的中值不确定性分别约为4、18和4 km s-1。我们提供了开普勒场中总共148，590颗恒星的三维速度。这些3D速度可以使运动学年龄测定，银河系恒星种群研究和其他科学研究使用的基准样本，充分研究开普勒恒星。虽然这里使用的方法广泛适用于天空中的目标，但我们的先验是专门从开普勒场构建的。在将这种方法推广到银河系其他地区时，应注意使用适当的先验知识。
Precise Gaia measurements of positions, parallaxes, and proper motions provide an opportunity to calculate 3D positions and 2D velocities (i.e., 5D phase-space) of Milky Way stars. Where available, spectroscopic radial velocity (RV) measurements provide full 6D phase-space information, however there are now and will remain many stars without RV measurements. Without an RV it is not possible to directly calculate 3D stellar velocities; however, one can infer 3D stellar velocities by marginalizing over the missing RV dimension. In this paper, we infer the 3D velocities of stars in the Kepler field in Cartesian Galactocentric coordinates (v x , v y , v z ). We directly calculate velocities for around a quarter of all Kepler targets, using RV measurements available from the Gaia, LAMOST, and APOGEE spectroscopic surveys. Using the velocity distributions of these stars as our prior, we infer velocities for the remaining three quarters of the sample by marginalizing over the RV dimension. The median uncertainties on our inferred v x , v y , and v z velocities are around 4, 18, and 4 km s−1, respectively. We provide 3D velocities for a total of 148,590 stars in the Kepler field. These 3D velocities could enable kinematic age-dating, Milky Way stellar population studies, and other scientific studies using the benchmark sample of well-studied Kepler stars. Although the methodology used here is broadly applicable to targets across the sky, our prior is specifically constructed from and for the Kepler field. Care should be taken to use a suitable prior when extending this method to other parts of the Galaxy.