NOEMA data. Upper panel: the gray-scale map reproduces the 1.37 mm continuum emission, plotting values in the range 10–35 mJy beam⁻¹. The colored dots give the (Gaussian-fitted) positions of the channel emission peaks for the CH₃ CN J_K = 12_K–11_K (K = 3–6) and HC₃N J = 24–23 lines; the colors denote the channel V_LSR. The colored contours indicate the half-peak level for the CH₃CN J_K = 12₃-11₃ emission in individual channels. The yellow contours show the JVLA A-Array continuum at 1.3 cm (Moscadelli et al. 2016), showing levels at 70, 80, and 90% of the peak emission of 0.50 mJy beam⁻¹. Lower panel: the gray-scale map, yellow contours, and colored dots have the same meaning as in the upper panel. Only the channel emission peaks at the extreme blue- and red-shifted velocities (reported in the lower right corner of the panel) are shown. The white continuous and dashed lines indicate the best-fit major axis of the distribution of the peaks and the corresponding fit uncertainty, respectively.