Maps of the integrated intensity (upper panels) and velocity field (bottom panels) of a) CH₃OCHO (26_6,20–25_6,19); b) CH₃OCHO (27_7,21–26_7,20); c) H₂CS (10_1,9–9_1,8), d) HNCO (16_1,16–15_1,15); e) SO₂ (18_4,14–18_3,15); and f) HC₃N (37–36) 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 = 0.06), 3σ (3σ, with σ = 0.04), 5σ (10σ, with σ = 0.16), 5σ (10σ, with σ = 0.10), 5σ (5σ, with σ = 0.20), and 5σ (10σ, with σ = 0.11) for core A; and 3σ (3σ, with σ = 0.03), 1σ (1σ, with σ = 0.02), 5σ (5σ, with σ = 0.09), 5σ (5σ, with σ = 0.06), 5σ (5σ, with σ = 0.10), and 5σ (10σ, with σ = 0.07) for core B. See details and description of symbols in Fig. 4.