P₃₅₃/p_max ratio as a function of the modified blackbody temperature (top panel) and as a function of the normalized radiance ℛ /A_V (bottom panel). The bottom panel does not include stars without A_V and p_V measurements. The grey curves show the model for varying intensity of the radiation field (0.1 ≤ G₀ ≤ 3).The grey square marks the position of the standard model. The color and symbol scheme for the observarions are the same as in Fig. 2.