Upper panels: C₂H emission spectra taken at three representative knots of the SB ring (SB-I, SB-II, and SB-III). Lower panels: C₂H spectra taken at three representative knots of the outflow region (OUT-I, OUT-II, and OUT-III). The apertures used to extract the spectra correspond to the beam size at the location of each knot ( at PA = 69°). The positions of the knots are defined in Fig. 2. The velocity scale for each spectrum has been derived for the strongest C₂H line at 87.317 GHz (rest frequency) and is relative to = 1136 km s^-1. The (red) curves show the composite Gaussian profiles of the best fit to the emission, as described is Sect. 3.3.