Light Element Abundances and Multiple Populations in M10
  We present CN and CH band measurements for 137 RGB and AGB stars in the
Galactic globular cluster M10. Our measurements come from low resolution
spectroscopy taken with the Hydra spectrograph on the WIYN-3.5m telescope. We
use these measurements to identify two populations of stars within the cluster,
a CN-normal and CN-enhanced, and find that in our sample 60% of stars are
CN-enhanced. Our large sample allows us to conduct a detailed analysis on the
carbon and nitrogen abundances and the radial distribution of each population
separately. Our analysis of the radial dependence shows that each population
has the same radial distribution in the cluster, which is likely due to the
cluster being dynamically evolved. We also compare our results to other methods
of classifying multiple populations in globular clusters such as the Na-O
anti-correlation and the HST pseudo-color magnitude diagrams. We find that
these three methods of identifying multiple populations are in good agreement
with each other for M10 and all lead to an estimate of the fraction of second
generation stars approximately equal to 60%. Among AGB stars, when classified
by the CN band, there appears to be a lack of second generation stars when
compared to the RGB stars. However, when classified by [N/Fe], we find a
similar 60% of AGB stars in the second generation. Finally, we use the measured
carbon and nitrogen abundances in RGB stars to study the change of each element
with magnitude as stars evolve up the RGB, comparing the results to globular
clusters of similar metallicity, M3 and M13.
