Astronomical environments covered by the parameter space through our choice of the ionizing luminosity Q₀ and density n_H. Among the environments shown are ultra-compact and hyper-compact  H II regions (UC- H II/HC- H II), compact  H II regions (C- H II), and evolved  H II bubbles, as discussed in this work. We also show super star clusters (SSCs) in the Local Group, merging galaxies, starburst galaxies, and ultra luminous infrared galaxies (ULIRGs). Prototypical candidates of each class are denoted between brackets (for references, see Fig. 6).