lines in photospheric granulation

The possibility of significant systematic errors due to the use of 1D homogeneous atmospheres in lithium-abundance determinations of cool stars motivates a study of non-localthermodynamic-equilibrium (nlte) effects on Li I line formation in a 3D solar-granulation simulation snapshot. The nlte effect on the equivalent width of the 671nm resonance line is small in 1D models or in integrated light from the granulation model. The line-strength variations over the granulation pattern are however markedly different in nlte compared to lte – observations of this may provide diagnostics to nlte effects. The effects of horizontal photon exchange found in the granulation model are moderate and due entirely to bound-bound processes, ultraviolet overionization is unimportant. Subject headings: line: formation — Sun: abundances — Sun: granulation — stars: abundances — stars: atmospheres