Velocity-integrated molecular emission maps. We show the six molecular species for which the signal-to-noise ratio is good. For C₄H, HCS⁺, HCO, HN¹³C, and ³⁴SO, the maps are too noisy and we do not show them. The species and the E_up of the line used in temperature units are indicated in the top left corner of each frame. The two stars indicate the peak position of the millimeter-continuum cores N and S. The black circles highlight the primary beam at the rest frequency of each line (Table 2). The integrated emission was computed in the channels in which the intensity was higher than the 3σ rms level. The velocity intervals used are [−18.4;−16.5] km s⁻¹ for c-C₃H₂; [−19;−16] km s⁻¹ for H¹³CO⁺; [−18.75;−16;25] km s⁻¹ for CH₃OH (from the line centred at ~96.7414 GHz) at [−20;−14] km s⁻¹ for CS; [−19.5;−15.5] km s⁻¹ for SO; [−18.8;−16.2] km s⁻¹ for H₂CO (from the line centred at ~140.8395 GHz). The seven regions highlighted in black are those analysed in detail in Sect. 3.4, and they generally correspond to the 5σ rms emission contour of the corresponding integrated-intensity map (within the ALMA primary beam).