a) Galactic H ii region RCW 120 in the mid-IR from Spitzer at 24 μm. A dark spot below the position of the star is from saturated pixels. b) Synthetic observation at 24 μm of dust emission from the simulation WV04 (sil2.0). c) Synthetic observation at 24 μm of dust emission from the simulation HV04 (sil2.0). The black cross shows the position of the ionizing star. The coordinates are in arcseconds relative to the star’s position. The units are in MJy sr^-1, shown in logarithmic units (i.e. log ₁₀I). The outer arc/ring is the H ii region boundary and the inner arc may show the edge of the stellar wind bubble. Images are generated from the simulations after 0.4 Myr of evolution in this and the following figures (see Fig. 2).