Maps of the integrated intensity (upper panels) and velocity field (bottom panels) of a) CH₃CN K = 2 at 349.426 GHz; b) CH₃CN K = 8 at 349.024 GHz; c) CHCN K = 2 at 349.254 GHz; and d) CH₃CN v₈ = 1K,l = 3,1 at 350.552 GHz towards cores A and B. For the different panels, the starting (and increasing contour levels in terms of σ, in Jy beam^-1 km s^-1) are 5σ (10σ, with σ = 0.15), 5σ (10σ, with σ = 0.15), 3σ (3σ, with σ = 0.10), and 5σ (10σ, with σ = 0.10) for core A; and 5σ (5σ, with σ = 0.09), 4σ (4σ, with σ = 0.09), 2σ (2σ, with σ = 0.06), and 3σ (3σ, with σ = 0.06) for core B. See details and description of symbols in Fig. 4.