Binned azimuthally averaged amplitude profiles in orange (B6) and violet (B3) for each source are shown on the left y-axis of each panel. The total emission spectral index (black line) of the emission as a function of uv-distance (bottom) or, equivalently, the probed physical scale θ =1.22 λ/uv-distance (top), are shown on the right y-axis of each panel. L1527 IRS was taken from Cacciapuoti et al. (2023), where only 1.2 and 3.1 mm wavelengths (similar to FAUST) were colored according to the other sources, while the other frequencies were plotted in grey.