Program: GN-2009B-C-5

Our ultimate goal is to illuminate the origins of the ``light metals'' in the ancient halos of spiral galaxies like ours. We propose here to measure emission line fluxes in the blue in nine planetary nebulae (PNe) in the halo/thick disk of M31. We will combine this data with red spectral data already in hand to determine the abundances of light metals (N, O, Ne, [C via HST], and possibly S) in these PNe, which represent the ISM from which the oldest surviving stars in M31 formed. The progenitors of these PNe formed from the ``second ISM'': a medium enriched only by the earliest supernovae. Determining the provenance of the material that formed the progenitors of currently-observable PNe in M31 is an important step toward understanding the process of galaxy development and the early production of the light metals. Our results will be compared with published results of [Fe/H] in red giants in the same stellar population and compared to light metal abundances in far younger PNe observed in M31 and the Milky Way.