Flux of the 1–0 S(1) line in arbitrary units (top row panels), ratio of the total H₂ IR lines luminosity to the central star luminosity (middle), and 1–0 S(1) luminosity to total H₂ IR lines luminosity ratio (bottom) as a function of T _⋆ . Curves for different L _⋆ , n_H, and M_d/M_g are shown, respectively, in the left, middle, and right panels in each row. The line styles are the same as in Fig. 2. In the bottom left panel, the curves for L _⋆  =  100 and 3000 L_⊙ coincide. The standard PN values are adopted for the parameters not mentioned.