Scatter plot of F_excess/F_12,phot versus F_12,phot for Sample B stars. The vertical dashed lines represent the boundaries at F_12,phot = 10 mJy (blue) and F_12,phot = 600 mJy (red), indicating different flux regimes. The bottom panel is divided into three regions based on F_12,phot : red dots represent stars with F_12,phot < 10mJy; blue dots represent stars with 10mJy ⩽0 F_12,phot ⩽ 600 mJy; green dots represent stars with F_12,phot > 600 mJy. And the black line represents the empirical measure of uncertainty 3σ for each regime.