Dependence on excitation potential for Fe I lines of similar strength in five different models. Left to right: ‘K8 V’. ‘K2 V’, ‘G1 V’, ‘F7 V’, and ‘F3 V’. Low-excitation profiles and bisectors are indicated in the top rows, high-excitation ones atbottom. Long-dashed profiles and bisectors are shown for stellar disk-center positions μ = 1; short-dashed for μ = 0.41, and dotted for μ = 0.09. Bisector scales (at center) are expanded tenfold relative to the line profiles.