Top panel: residual radial profiles from the models in Fig. 1 with an evaporation temperature of CO T_CO = 19–20 K and a constant abundance X_in = 5.0 × 10⁻⁵. Bottom panel: vertically averaged abundance estimate of the radial curves of the top panel using the same excitation temperatureprofile and prescription proposed by Salinas et al. (2017) to convert emission to column densities. The 50 AU bar corresponds to the semiminor axis of the synthesized beam and serves as a measure of the spatial resolution.