IR O I triplet, [O I] lines in F-K dwarfs/giants

The formation of the triplet O I lines was found to be well described by the classical two-level-atom scattering model, and the non-LTE correction is practically determined by the parameters of the line-transition itself without any significant relevance to the details of the oxygen atomic model.

This simplifies the problem in the sense that the non-LTE abundance correction is essentially determined only by the line-strength (W_{lambda}_), if the atmospheric parameters of Teff, logg, and {xi} are given, without any explicit dependence of the metallicity; thus allowing a useful analytical formula with tabulated numerical coefficients. On the other hand, our calculations lead to the robust conclusion that LTE is totally valid for the forbidden [O I] lines.