Results from CO analysis for IK Tau. The left panel shows the observed intensities (see Table A.3) as black filled circles and the calculated ones as red empty circles. The right panel shows χ² as a function of the logarithm of the mass-loss rate, log Ṁ, and the exponent of the gas kinetic temperature radial profile, δ. The white contours correspond to 1, 2, and 3σ levels. Similar plots for other stars are shown in Fig. A.3.