Distributions of the peaks of the emission in the velocity channels of various lines observed in IRAS 20126+4104. The error bars are the formal errors on the Gaussian fits. The offsets are relative to the phase center of the observations. The black cross marks the position of the 1.4 mm continuum peak. (a) Plot obtained from the CH₃CN(12–11) lines. The color coding is as follows: K=2 black, 3 red, 4 green, 5 blue, 7 cyan, 8 yellow, and v₈=1 magenta. The dashed lines are linear fits to the points obtained by fitting Y vs X and X vs Y; the solid line is the mean of the two. (b) Same as panel a but for the ¹³CH₃CN(13–12) components: K=2 black, 3 red, 4 green, and 5 blue. (c) Same as panel a but for the ${\mathrm{C}\mathrm{H}}_3^{13}\mathrm{C}\mathrm{N}$(12–11) components: K=2 black, 4 red. (d) Same as panel a but for the DCN(3–2) line.