Averaged spectra of different molecules in clump C4, calculated from the regions indicated by the red elliptical area in Fig. D.1. This includes in blue the ¹²CO (3–2), in red the C¹⁸O (1–0), and in green the N₂H⁺ (1–0) transitions. The C¹⁸O (1–0) and N₂H⁺ (1–0) data were obtained from Zhang et al. (2017) using observations from the IRAM 30 m telescope. Note that the condition for generating a blue-red asymmetry spectrum is that the cloud must exhibit a central condensation of material. We assumed that clump C4 satisfies this condition.