Properties of the line-emitting area of the CO₂ line at 14.98299 μm, calculated using the escape probability method for our series of models with a gas-to-dust ratio of 100: 1. Left-hand panel: average gas and dust temperatures, weighted by the mass of each grid point (left-hand y-axis), and the difference between them (on the right-hand y-axis). Right-hand panel: inner (“x15”) and outer (“x85”) radial boundaries of the line-emitting region (on the left-hand y-axis), and the vertical boundaries of the line-emitting region (on the right-hand y-axis). If the line-emitting region is shaped like a box, as in Fig. 3, then “min z85” is the lower-left corner, and “max z15” isthe upper-right corner.