We have used Hubble Space Telescope and ground-based photometry to determine total V-band magnitudes and mass-to-light ratios of more than 150 Galactic globular clusters. We do this by summing up the magnitudes of their individual member stars, using colour-magnitude information, Gaia DR2 proper motions, and radial velocities to distinguish cluster stars from background stars. Our new magnitudes confirm literature estimates for bright clusters with $V<8$ , but can deviate by up to two magnitudes from literature values for fainter clusters. They lead to absolute mass-to-light ratios that are confined to the narrow range $1.4<M/L_V<2.5$ , significantly smaller than what was found before. We also find a correlation between a cluster’s $M/L_V$ value and its age, in agreement with theoretical predictions. The $M/L_V$ ratios of globular clusters are also in good agreement with those predicted by stellar isochrones, arguing against a significant amount of dark matter inside globular clusters. We finally find that, in agreement with what has been seen in M 31, the magnitude distribution of outer halo globular clusters has a tail towards faint clusters that is absent in the inner parts of the Milky Way.

中文翻译：

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银河球状星团的绝对波段大小和质光比

我们用过哈勃太空望远镜和基于地面的光度法来确定总五超过 150 个银河球状星团的波段大小和质光比。我们通过使用颜色星等信息来总结它们各个成员恒星的星等来做到这一点，盖亚DR2 自行和径向速度，以区分星团恒星和背景恒星。我们的新星等证实了文献对明亮星团的估计 $V<8$ ，但对于较暗的星团，最多可以偏离文献值两个数量级。它们导致被限制在狭窄范围内的绝对质光比 $1.4<M/L_V<2.5$ , 比以前发现的要小得多。我们还发现了集群之间的相关性 $M/L_V$ 价值及其年龄，与理论预测一致。这 $M/L_V$ 球状星团的比率也与恒星等时线预测的结果非常吻合，这与球状星团内的大量暗物质相矛盾。我们最终发现，与在 M 31 中看到的一致，外晕球状星团的星等分布有一条朝向银河系内部不存在的微弱星团的尾巴。