SiO and dense gas distribution and position-velocity maps. Upper panel (a) Integrated intensity map of SiO (21) (76.7–106.7 km s^–1, gray scale) overlaid with the n(H₂) levels of 10⁶, 10⁶⁵, 10⁷ cm^–3 (in contours of various shades of green, respectively). The 3 mm continuum peaks of MM2 and MM3 are indicated as magenta crosses. The red and blue thick lines indicate the ridge of the emission of the blue-shifted and red-shifted SiO in panel b. (b) The integrated intensity maps (velocity ranges indicated in the plot) of the SiO (2–1) blue-shifted and red-shifted emission. The crosses in orange (with at least one broader velocity component of σ_v > 0.85 km s^–1, see Sect. 4) and black indicate the NH₂D cores. For plots a and b, RA and Dec offsets correspond to the relative position with respect to 3 mm continuum peak of MM3. Lower panel: position-velocity diagrams of SiO (2–1) (contour levels of 0.2–1.4K km s^–1 with six intervals) and CH₃OH 5_1,5 –4₀,₄ (contour levels of 0.1–10.3 K km s^–1 with six intervals) line along the three cuts U, M, and L, as in the upper panel. The colour-shaded regions indicate the n(H₂) levels of 10⁶, 10⁶⁵, and 10⁷ cm^–3 (in light blue, blue, and purple). The V_LSR of MM2 and MM3 are indicated as red and blue horizontal lines (93.9 km^–1 and 91.3 km^–1). Blue vertical dotted lines indicate the positions of the 3 mm continuum peak of MM2 and MM3.