STELLAR OXYGEN ABUNDANCES .1. A RESOLUTION TO THE 7774-ANGSTROM-OI ABUNDANCE DISCREPANCY

We investigate the discrepancy between [O/Fe] ratios of metal-poor stars derived from the 7774 angstrom O I triplet and [O/Fe] ratios determined from other oxygen lines. We propose a possible resolution to this discrepancy which also eliminates the correlation of [O/Fe] and T(eff) found in a recent 7774 angstrom O I analysis. The equivalent widths of Abia & Rebolo [ApJ, 347, 186 (1989)] are found to be systematically too high by 25%. Arguments are presented that current temperature estimates for halo stars are 150-200 K too low. Using the guidance of both model atmospheres and other empirical color-T(eff) relations, we construct new color temperature relations for metal-poor stars. These relations are tied to the temperature scale of Saxner & Hammarback [A&A, 151, 372 (1985)] for metal-rich stars. We use (b-y) and (V-K) indices to redetermine values of T(eff) for a handful of halo stars. (B - V)-T(eff) relations which do not take into account the effects of metallicity are found to be inadequate. Revised [O/Fe] ratios are determined using the new temperature scale. The mean abundance ratio of the reanalyzed halo dwarfs is [O/Fe] approximately + 0. 52. There is no trend of [O/Fe] with [Fe/H] or T(eff).