Velocity dispersions and mass-to-light ratios for 9 globular clusters in M31

We present internal velocity dispersion determina- tions from high-resolution spectroscopic observations of a sam- pleofnineglobularclustersinM 31.Comprehensivenumerical simulations are used to show that the typical uncertainty of our velocity dispersion measurements is 5%. Using these new ve- locity dispersions together with structural parameters derived from HST observations, we estimate the M=LV ratios of these clusters and nd that they are typical of those measured for Galactic clusters. We show relations between velocity disper- sion, luminosity and physical scales for globular clusters be- longing to the Galaxy, the Magellanic clouds, Fornax, M 31, and Centaurus A. The mean relations and the degree of scatter are similar in all galaxies. This reveals remarkable similarities, intermofstructureandM=LV ratio,betweentheglobularclus- ters belonging to these different galaxies. We briefly discuss the possible use of individual globular clusters as extragalactic dis- tance indicators.