Equatorial density distribution of the gas in the extended version of our best-fit model, which intends to include not only CO-rich gas, but also the adjacent regions in which molecules are assumed to be photodissociated (see Sect. 4.3 for details.) Top: density distribution in the plane of the equator. Middle: density distribution in the y = 0 plane. Bottom: same, but for the x = 0 plane. All representations share the same units and scales as in Fig. 6.