Cool Star Oxygen Abundances from Spectral Synthesis of TiO Bands

We have used spectral synthesis of the γ R₂ 0-0 TiO band at 7054 Å to determine oxygen abundances in dwarfs previously analyzed for iron and titanium abundances from their atomic lines. With the abundances of Fe and Ti held fixed, the band profiles are sensitive to the oxygen abundances. For the late K and M dwarfs analyzed, the [O/Fe] trend agrees with previous work for higher mass stars from [Fe/H] = +0.1 to [Fe/H] = -1.5. Beyond [Fe/H] = -1.5, the TiO band becomes too weak to analyze except in cooler stars for which Ti abundances are difficult to determine because their Ti I lines are frequently blended. We find that the abundance trend derived for our stars matches those derived for solar neighborhood stars by other methods.