  The abundance of oxygen was determined for selected very metal-poor G-K stars
(six giants and one turn-off star) based on the high S/N and high-resolution
spectra observed with Keck HIRES in the red through near-IR region comprising
the permitted O I lines (7771-5, 8446) along with the [O I] forbidden line at
6363 A. It turned out that both the abundances from the permitted line
features, O I 7771-5 and O I 8446, agree quite well with each other, while the
forbidden line yields somewhat discrepant and divergent abundances with a
tendency of being underestimated on the average. The former (7773/8446)
solution, which we believe to be more reliable, gives a fairly tight [O/Fe] vs.
[Fe/H] relation such that increasing steadily from [O/Fe] = 0.6 (at [Fe/H] =
-1.5) to [O/Fe] = 1.0 (at [Fe/H] = -3.0), in reasonable consistency with the
trend recently reported based on the analysis of the UV OH lines. We would
suspect that some kind of weakening mechanism may occasionally act on the
formation of [O I] forbidden lines in metal-poor stars. Therefore, [O I] lines
may not be so a reliable abundance indicator as has been generally believed.
