Comparison between the observed C¹⁸O (1–0) (top panels) and H¹³CO⁺ (1–0) (bottom panels) integrated intensities as a function of the offset from core center and the predictions of our models including cosmic-ray photodesorption (CRP) and grain-growth. In each panel the dotted curve corresponds to the fiducial model (no CRP and a constant grain size), the dashed curve corresponds to the model with CRP only, and the solid curve corresponds to the best-fit model (with both CRP and grain-growth).