Model DR_SS at t = 400 yr and an inclination angle i = 30°. The results are presented for four different values of the jet–ambient gas mixing degree j_mix (from top to bottom): 0.0, 0.3, 0.6, 1.0. Left: maps of H₂ column density obtained by integration over the velocity range between 1 and +150 km s⁻¹. Right: mass–velocity relationship obtained for the molecular gas (black) and the total gas (blue). The best-fitting power laws for the three velocity intervals: v ≤10 km s⁻¹ (left; dashed red), 10 km s⁻¹ < v < 30 km s⁻¹ (middle; dashed green) and 30 km s⁻¹ < v < 60 km s⁻¹ (right; dashed red) are drawn. The index γ for each one of these intervals are shown inside each panel. The vertical arrows indicate the position of bumps in the total mass–velocity profile (see text).