2015A&A...581A..70K

We present a grid of computed non-local thermodynamic equilibrium (NLTE) equivalent widths (EW) and NLTE abundance corrections for four BaII lines: 4554, 5853, 6141, and 6496Å. The grid can be useful in deriving the NLTE barium abundance in stars having parameters in the following ranges: effective temperature from 4000 K to 6500K, surface gravity logg from 0 to 5, microturbulent velocity 0km/s to 3km/s, metallicity [Fe/H] from -2 to +0.5, and [Ba/Fe] from -0.4 to +0.6. The NLTE abundance can be either derived by EW interpolation (using the observed BaII line EW) or by using the NLTE correction applied to a previously determined LTE abundance. BaII line equivalent widths and the NLTE corrections were calculated using the updated MULTI code and the BaII atomic model that was previously applied to determine the NLTE barium abundance in different types of stars. The grid is available on-line through the web, and we find that the grid Ba NLTE corrections are almost as accurate as direct NLTE profile fitting (to within 0.05-0.08dex). For the weakest BaII line (5853Å) the LTE abundances almost agree with the NLTE abundances, whereas the other three BaII lines, 4554, 6141, and 6496Å, need NLTE corrections even at the highest metallicities tested here. The 4554Å line is extremely strong and should not be used for abundance analysis above [Fe/H]=-1. Furthermore, we tested the impact of different model atmospheres and spectrum synthesis codes and found average differences of 0.06dex and 0.09dex, respectively, for all four lines. At these metallicities we find an average ΔNLTE of ±0.1dex for the three useful Ba lines for subsolar cool dwarfs.