The Initial Mass Functions of Magellanic Cloud star clusters

Luminosity and Initial Mass Functions (IMF) are determined for a sample of six Magellanic Cloud (MC) star clusters. The program objects span a large range in age (10 Myr to 2.5 Gyr), and include the possibly very metal-poor cluster NGC 330 in the SMC. The procedures involved in deriving the luminosity and mass functions are very briefly described. They key result is that the IMFs of all six clusters are consistent with a single IMF slope ofx=2.5, where the Salpeter value is 1.35. This result does not depend on the passband or on the detailed stellar evolution models that are used. A comparison is described between the present results and the few previous and ongoing studies of mass functions of MC clusters. Taken at face value, this comparison suggests that the IMF slopes of MC clusters vary over a wide range, and no apparent correlation with this slope and any global cluster properties are evident. A further comparison with results for galactic clusters (both open and globular) does not clarify the problem. It may be that the slope of the IMF on the scale of even rather massive star clusters is determined either randomly, or by some mechanism we have yet to identify and which does not correlate with obvious cluster properties.Visiting astronomer at the Cerro Tololo Interamerican Observatory, National Optical Astronomy Observatories, operated by the Association of Universities for Research in Astronomy, Inc., under contract with the National Science Foundation.