Aula
The SDSS Apache Point Observatory Galactic Evolution
Experiment (APOGEE) has
collected high resolution near-IR spectra of several hundred thousand stars
across the Milky Way. I'll describe some observational results about the
spatial variation of chemical abundances as a function of Galactocentric
radius and distance from the midplane, discussing mean abundances,
metallicity
distribution function, and the variation of abundance ratios of multiple
elements. Additional information related to stellar ages can be obtained
from [C/N] for red giant stars. Several lines of evidence suggest that
radial
migration has had a significant impact on the Galactic disk. The
observed patterns of
abundance ratios may provide observational constraints on
nucleosynthetic yields.