We report the first determination of the distance to the Galactic centre based on the kinematics of halo objects. We apply the statistical-parallax technique to the sample of ~2500 Blue Horizontal Branch (BHB) stars compiled by Xue et al. (2011) to simultaneously constrain the correction factor to the photometric distances of BHB stars as reported by those authors and the distance to the Galactic centre to find R0=8.2+/-0.6 kpc. We also find that the average velocity of our BHB star sample in the direction of Galactic rotation, V0=-240+/-4 km/s, is greater by about 20 km/s in absolute value than the corresponding velocity for halo RR Lyrae type stars (V0=-222+/-4 km/s) in the Galactocentric distance interval from 6 to 18 kpc, whereas the total (sigma V) and radial (sigma r) velocity dispersion of the of the BHB sample are smaller by about 40-45 km/s than the corresponding parameters of the velocity dispersion ellipsoid of halo RR Lyrae type variables. The velocity dispersion tensor of halo BHB stars proved to be markedly less anisotropic than the corresponding tensor for RR Lyrae type variables: the corresponding anisotropy parameter values are equal to beta(BHB)=0.51+/-0.02 and beta(RR)=0.71+/-0.03, respectively.

中文翻译：

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校准 BHB 星距标度和到银河中心的 Halo 运动学距离

我们报告了基于晕天体运动学对银河系中心距离的首次确定。我们将统计视差技术应用于 Xue 等人编制的约 2500 颗蓝色水平分支 (BHB) 恒星的样本。(2011) 同时将校正因子限制为这些作者报告的 BHB 恒星的光度距离和到银河系中心的距离，以发现 R0=8.2+/-0.6 kpc。我们还发现，我们的 BHB 恒星样本在银河系自转方向上的平均速度，V0=-240+/-4 公里/秒，绝对值比光环 RR 天琴座的相应速度高约 20 公里/秒在半乳中心距离区间为 6 到 18 kpc 的类型星 (V0=-222+/-4 km/s)，而 BHB 样本的总 (sigma V) 和径向 (sigma r) 速度色散比 halo RR Lyrae 型变量的速度色散椭球的相应参数小约 40-45 km/s。光环 BHB 星的速度色散张量被证明明显比 RR Lyrae 型变量的相应张量的各向异性小：相应的各向异性参数值等于 beta(BHB)=0.51+/-0.02 和 beta(RR)=0.71+ /-0.03，分别。