The Mass Function of Young Star Clusters in the "Antennae" Galaxies

We determine the mass function of young star clusters in the merging galaxies the ``Antennae'' (NGC 4038/39) from deep images taken with the WFPC2 on the refurbished Hubble Space Telescope (HST). This is accomplished by means of reddening-free parameters and a comparison with stellar population synthesis tracks to estimate the intrinsic luminosity and age and hence the mass of each cluster. We find that the mass function of the young star clusters (with ages <~ 160 Myr) is well represented by a power law of the form psi(M) ~ M^{-2} over the range 10^4 < M < 10^6 solar masses. This result may have important implications for our understanding of the origin of globular clusters during the early phases of galactic evolution.