Top panels: integrated-intensity profiles of lines of HCN isotopologs. The ribbons show the standard deviation across each annulus, divided by the square root of the number of independent beams. The intensity is expressed in brightness temperature under the Rayleigh-Jeans approximation. The dashed black line is the integrated-intensity profile of the 855 μm continuum (Isella et al. 2019; Benisty et al. 2021). The hatched region shows the beam major axis of each line. Bottom row: results of the radial rotational diagram analysis. The solid lines in the left and middle panels show the 50th percentile of the column density profiles (H¹³CN in blue and HC¹⁵N in pink) and of the excitation temperature (black). The ribbons show the 16th and 84th percentiles of the posterior distributions. The right panel represents the radial profiles of the optical depth for the analyzed molecular lines of H¹³CN and HC¹⁵N, and the related uncertainty is shown for the H¹³CN (3–2) line for reference because it is representative of the typical uncertainty. The dashed black line shows the τ = 1 level.