¹²CO(2−1) (grey), SiO(5−4) (blue), SO(6₅−5₄) (magenta), ¹³CO(2−1) (cyan), and p-H₂CO(3₀₃−2₀₂) (black) spectra at the EHV peak (see Fig. 5). The p-H₂CO(3₀₃−2₀₂) spectrum was observed with WideX (see Appendix B) at the spectral resolution of ~2.7 km s^-1; all other spectra have thus been smoothed to the same spectral resolution. The ¹²CO(2−1) data have been convolved to match the angular resolution at 1.4 mm (18).