Dependency of the reconstructed source size (half-light radius) of the line emission regions with transition or frequency. Black dots show reconstructed CO line emission regions as a function of the J transition and the observed frequency. Purple triangles show reconstructed H₂O line emission as a function of the observed frequency. The dotted lines represent the size (r_1/2) of the dust for different wavelengths, blue for 870 μm, red for 2 mm, and green for 3 mm continuum emission.