ESO452-SC11: The lowest mass globular cluster with a potential chemical
  inhomogeneity
  We present the largest spectroscopic investigation of one of the faintest and
least studied stellar clusters of the Milky Way, ESO452-SC11. Using the
Anglo-Australian Telescope AAOmega and Keck HIRES spectrographs we have
identified 11 members of the cluster and found indications of star-to-star
light element abundance variation, primarily using the blue cyanogen (CN)
absorption features. From a stellar density profile, we estimate a total
cluster mass of $(6.8\pm3.4)\times10^3$ solar masses. This would make
ESO452-SC11 the lowest mass cluster with evidence for multiple populations.
These data were also used to measure the radial velocity of the cluster
($16.7\pm0.3$ km s$^{-1}$) and confirm that ESO452-SC11 is relatively
metal-rich for a globular cluster ([Fe/H]$=-0.81\pm0.13$). All known massive
clusters studied in detail show multiple populations of stars each with a
different chemical composition, but many low-mass globular clusters appear to
be chemically homogeneous. ESO452-SC11 sets a lower mass limit for the multiple
stellar population phenomenon.
