Abundances in the Galactic Center

Abstract

Abundance measurements in the Galactic Center (GC) probe material with a nucleosynthetic history unique in our Galaxy. The measurements are of two types: probing interstellar and stellar material. Measurements of gas-phase abundances are mostly toward SgrB2 and SgrA. They reflect the current state of nuclear evolution in the GC and include several important isotope abundance ratios. The isotope ratios provide the most accurate information and allow for comparison with results elsewhere in the interstellar medium. The second type of measurement is of abundances in (and around) stars, yielding chemical abundances in the bulge and disc populations, and reflecting the state of nuclear evolution when the stars were born.When combined with our knowledge of evolution in the solar neighborhood, several of the results are consistent with the the greater nuclear “maturity” of the inner Galaxy. However, there are several important exceptions, which point to the fact that we really do not understand nuclear processing in the GC region. Some of the open issues may be resolved observationally, and with new infrared and millimeterwave techniques a clear opportunity exists to improve the observational record. Results should increase our understanding of stellar nucleosynthesis and of the history of star formation in the GC.