Magnitudes and Mass-to-Light Ratios of Galactic Globular Clusters
Absolute V-band magnitudes and mass-to-light ratios of Galactic globular clusters
We present new total magnitudes and absolute mass-to-light ratios for more than 150 galactic globularclusters.We do this by summing up the magnitudes of their individual member stars, using color-magnitude information, hst and ground-based photometry to determine total magnitudes and absolute mass-to-light ratios of their individual member stars.We 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 absolute mass-to-light ratio and its age, in agreement with theoretical predictions.The absolute mass-to-light 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 the outer halo globular clusters, 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.
