Time evolution of the ¹³CO intensityprofiles for our grid of models, after including the effects of chemical depletion of CO through grain surface chemistry (see Sects. 4.3 and F). Rows: models with equal stellar mass, columns: models with equal α_visc. The colors, going from red to blue, show the different time steps. For each model, the radius enclosing 90% of the total flux is indicated by a cross. A low stellar mass corresponds to a low stellar accretion rate, using the observational relation shown in Fig. 6 in Alcalá et al. (2017). Also owing to the setup, a low α_visc corresponds to a high viscous time (t_visc) and a high initial mass (M_init).