Influence of Inelastic Collisions with Hydrogen Atoms on Non-LTE Oxygen Abundance Determinations

We present the results of our modeling of the O I line formation under non-LTE conditions in the atmospheres of FG stars. The statistical equilibrium of O I has been calculated using Barklem’s quantum-mechanical rates of inelastic collisions with hydrogen atoms. We have determined the non-LTE oxygen abundance from atomic O I lines for the Sun and 46 FG stars in a wide metallicity range, ?2.6 < Fe/H] < 0.2. The application of accurate atomic data has led to an increase in the departures from LTE and a decrease in the oxygen abundance compared to the use of Drawin’s theoretical approximation. The change in the non-LTE abundance from the infrared O I 7771-5 Å triplet lines is 0.11 dex for solar atmospheric parameters and diminishes in absolute value with decreasing metallicity. We have revised the O/Fe]–Fe/H] relationship derived by us previously. The change in O/Fe] is small in the Fe/H] range from ?1.5 to 0.2. For stars with Fe/H] < ?1 the O/Fe] ratio has increased so that O/Fe] = 0.60 at Fe/H] = ?0.8 and rises to O/Fe] = 0.75 at Fe/H] = ?2.6.