Program: GS-2007A-Q-51

We propose to use Gemini-S/GNIRS in its high-resolution mode (R=18,000) to probe abundance patterns and chemical evolution in a heavily obscured field of the Galactic bulge, closer to the Galactic center than any previously studied bulge fields. Chemical abundances derived from stellar spectra can be used to study how chemical evolution has varied across different environments within the Galaxy. For example oxygen abundances, when combined with those from iron, provide information on the average star formation rate over time due to the differing timescales over which O and Fe are returned to the ISM as a result of stellar nucleosynthesis and evolution. This proposal takes advantage of IR spectroscopy to allow us to measure the rate of chemical evolution in the bulge in a field that would be much more difficult to reach in the optical, we will use abundances derived from red-giant members of the Galactic bulge in order to study its chemical enrichment history and the presence of metallicity gradients from comparisons with previously published studies further away. The GNIRS spectra to be obtained will offer a rich selection of molecular lines from CO, OH, CN, or HF from which C, N, F, and most importantly O abundances can be derived, along with key elements from atomic lines (Fe, Na, Si, Sc, Ti, or Ni). The derived abundance patterns will be compared to other populations in the Milky Way, such as the thin and thick disks and the halo in order to provide constraints to models of Galaxy formation.