EXTRAGALACTIC GLOBULAR-CLUSTERS .2. THE M31 GLOBULAR-CLUSTER SYSTEM

We derive metallicities for 150 globular clusters associated with M31, using the strengths of six absorption features in the cluster integrated spectra. The properties of the M31 cluster system are very similar to those of the Milky Way system. We find no dependence of metallicity on cluster luminosity. The number distribution as a function of metallicity is consistent with that of Milky Way clusters. There is evidence for a weak metallicity gradient as a function of projected radius. The mean metallicity [Fe/H] is equal to -1.2, slightly higher than the mean for the Milky Way system. The distinction between the rotation of the metal-rich and metal-poor clusters is most apparent in the inner 2 kpc. Inside that radius the high-metallicity M31 clusters appear to form a central rotating disk. At large radii, the cluster system appears to be rotating with a semiamplitude of 60 +/- 14 km s-1; outside 10' there appears to be no distinction in the rotation of the metal-poor and metal-rich clusters.