Gas number density (top), dust density (middle), and gas temperature (bottom) of our fiducial model for a Herbig star with a factor of 100 drop in gas density inside 30 AU. The cyan and orange contours indicate the τ = 1 surface of the ¹³CO J = 6−5 and J = 2−1 lines, respectively. The ¹³CO J = 2−1 transition is optically thin inside the dust cavity, and the J = 6−5 is optically thin inside the gas cavity; hence, these lines trace the midplane at these radii. We note that the dust cavity starts from 50 AU inward and the gas cavity from 30 AU. Only the regions with a gas density above 10⁷ cm⁻³ are shown. We note that the bottom panel is identical to the middle panel in Fig. 13.