SIMBAD references

Non-local thermodynamic equilibrium (non-LTE) calculations are performed for Nii in stellar atmospheric models appropriate to main-sequence B stars to produce new grids of equivalent widths for the strongest Nii lines commonly used for abundance analysis. There is reasonable agreement between our calculations and previous results, although we find weaker non-LTE effects in the strongest optical Nii transition, λ3995. We also present a detailed estimation of the uncertainties in the equivalent widths due to inaccuracies in the atomic data via Monte Carlo simulation and investigate the completeness of our model atom in terms of included energy levels. Uncertainties in the basic Nii atomic data limit the accuracy of abundance determinations to ~±0.10dex at the peak of the Nii optical spectrum near Teff ~ 24000K.