¹²CO(2–1) emission towards Knot-B. Significant ¹²CO (above the  ~5σ level) emission is detected, as a compact source  ~0.2″ away from the 1.3-mm continuum source tracing Knot-B. a) Shows the 1.3-mm continuum emission map, and the ¹²CO(2–1) integrated emission contours (blue from  − 8 km s^-1 to  + 3.0 km s^-1, red from  + 4.5 km s^-1 to  + 10 km s^-1). The solid contours are levels of 3σ and 5σ, and the dashed contours show the levels of  − 3σ, the rms noise being of 0.19 Jy/beam km s^-1. b) Shows the integrated ¹²CO spectrum of the emission feature associated with Knot-B. The middle black dashed vertical line shows the systemic velocity v_LSR ~ 3.8 km s^-1, while the colored dashed vertical lines show the position of the redshifted and blueshifted components seen in the ¹²CO(2–1) single-dish spectrum towards VLA1623 (André et al. 1990; Dent et al. 1995). The noise level is greater towards the spectrum of Knot-B than towards VLA1623 and Knot-A, because this source is located  ~10″ away from the phase center chosen for our observations.