The dependence of the mean polarization in the (1, 1) bandhead region on the μ value for several collisional coefficients   =  0.05 (solid lines), 0.3 (dashed lines), 0.7 (dashed dotted lines), and magnetic field strengths: 0 G, 20 G, 45 G, 60 G, and 90 G (from top to bottom) for each given value of . The five stars correspond to the five observed mean values.