NLTE effects

We have calculated a small number of NLTE models in order to investigate the importance of NLTE effects on the structure of the model atmospheres. The results for cooler models were discussed in and are not repeated here. Figures and 13 show an overview of selected NLTE species for models with $\hbox{$\,T_{\rm eff}$}=4000\,{\rm K}$ and $5600\,{\rm K}$ for $\log(g)=0.0$ and solar abundances. The total number of NLTE levels in each model is 4532 with a total of 47993 primary NLTE lines . The following species (and number of levels) were treated in NLTE: H I (30), Mg I (273), Mg II (72), Ca I (194), Ca II (87), Fe I (494), Fe II (617), O I (36), O II (171), Ti I (395), Ti II (204), C I (228), C II (85), N I (252), N II (152), Si I (329), Si II (93), S I (146), S II (84), Al I (111), Al II (188), K I (73), K II (22), Na I (53), and Na II (35). For most of the species, the departure coefficients are always close to unity, in particular for species with resonance lines and photoionization edges in the UV part of the spectrum. The species shown in Figure and 13 are the ones with the most pronounced departures from LTE. The departures are generally too small to significantly affect the structure of the atmospheres. However, NLTE effects do change the profiles of individual lines as shown in for Ti I lines. Therefore, abundance analyses of individual elements should take NLTE effects into account whenever possible.

for Ti I lines. Therefore, abundance analyses of individual elements should take NLTE effects into account whenever possible.