Non-LTE Equivalent Widths for NII with Error Estimates

TL;DR

This paper presents new non-LTE calculations for NII in B-star atmospheres, providing updated equivalent width grids, analyzing uncertainties, and assessing the impact of atomic data inaccuracies on abundance measurements.

Contribution

It offers the first comprehensive non-LTE equivalent width grids for NII with detailed error estimates and atomic data analysis for B-star abundance studies.

Findings

Non-LTE effects are weaker in the strongest optical NII lines.

Uncertainties in atomic data limit abundance accuracy to about +/-0.10 dex.

The model atom's completeness affects the reliability of the equivalent width calculations.

Abstract

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. 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 ~+/-0.10 dex at the peak of the NII optical spectrum near Teff~ 24,000 K.