The status of oxygen abundances of metal-poor stars

The sensitivity of various methods of oxygen-abundance determination to the structure of the model atmosphere in a classical analysis is described, wi th emphasis on the role of stellar effective temperature and the treatment of convection. Oxygen-abundance results presented during this meeting are o utlined. Because the oxygen diagnostics are sensitive in different ways to the choice of model stellar parameters and to the treatment of convection, it is not surprising that different methods applied by different groups giv e different results. Most are consistent with an increase in [O/Fe] as [Fe/ H] declines, but the slope is uncertain still, and the scatter is large at very low abundances. The trend may continue to low [Fe/H], but more stars a nd more checks are needed. (C) 2001 Published by Elsevier Science B.V.