Light-element Abundance Variations in the Milky Way Halo
  We present evidence for the contribution of high-mass globular clusters to
the stellar halo of the Galaxy. Using SDSS-II/SEGUE spectra of over 1900 G- and
K-type halo giants, we identify for the first time a subset of stars with CN
bandstrengths significantly larger, and CH bandstrengths lower, than the
majority of halo field stars, at fixed temperature and metallicity. Since CN
bandstrength inhomogeneity and the usual attendant abundance variations are
presently understood as a result of star formation in globular clusters, we
interpret this subset of halo giants as a result of globular cluster
dissolution into the Galactic halo. We find that 2.5% of our sample is
CN-strong, and can infer based on recent models of globular cluster evolution
that the fraction of halo field stars initially formed within globular clusters
may be as large as 50%.
