Program: GS-2011A-Q-22

The cluster BH176 has previously been classified as a nearby metal-rich (globular or open) cluster. We have shown in a recent paper that this is in fact a distant metal-poor globular cluster in the outer Galactic halo. The presence of 3 candidate carbon stars, a very rare occurrence in Galactic globular clusters, makes it about 3Gyr old. The aim of this project is to confirm the nature of this cluster, by performing GMOS medium-resolution spectroscopy of 119 red giant stars and the three candidate C stars in BH 176. We will determine the spectral type and measure the detailed abundances of the Carbon stars, which will be of great interest for stellar evolution theory. We will determine more accurately the cluster's metallicity and age by comparing the Lick indices with predictions of simple stellar population models. The Lick indices of individual stars will also allow us to study element abundance variations, like a bimodality of CN abundance. We will also provide an accurate estimate of the mean radial velocity of the cluster. These chemical and kinematical properties should enable us to assign this cluster to one of the various groups of globulars inventoried in the Galaxy.