Dense gas mass (n_H > 100 cm⁻³) in azimuthal bins (θ to θ + dθ) as a function of the angle θ around the center of the simulated bubbles, as derived directly from the column density maps in Figure 7. Solid lines show results for the left-hand bubble and dashed lines for the right-hand bubble. The top panels show plots for the early stage snapshot (3.5 Myr) and the bottom panel for the post-collision snapshot (5.5 Myr). The left-hand panels show the mass contained in "pie slices" of radius 0 to R₂ (as indicated in Figure 7), while on the right only the mass in a ring from R₁ to R₂ is calculated. Gray shaded areas mark the approximate location of the collision zone. These plots are for the pure hydrodynamic run only, since the results from the self-gravitating run are almost identical.