The kinematics and abundances of star clusters in the Large Magellanic Cloud

Abstract

We present velocities for 75 star clusters in the Large Magellanic Cloud (LMC), based on individual star measures at the Calcium triplet The spectra are also used to derive abundances for most of the clusters, and an age-metallicity relation is presented for the inner and outer regions. One half of the clusters are objects in the outer parts of the LMC (radius ≥5°), which had no previous velocity determinations. Published velocities for intermediate and old clusters are shown to have had systematic errors. We compare these velocities with various rotation curve analyses of the LMC, and test aspects of the twisted disk model of Freeman et al. (1983, hereafter FIO). Our outer cluster sample and the intermediate age inner clusters form a disk which agrees with the parameters of the optical isophotes and inner HI rotation curve. The oldest clusters are still enigmatic; they appear to be flattened and rotate much as FIO have described, although the parameters are poorly determined in this small sample.