Top row: spectral index maps, applying a filter to keep only the pixels with more emission than 5σ in both bands. The beam size is shown in the bottom left corner, along with a dark line representing a 0.5′′ scale. Middle row: spectral index cuts along the major axis. Bottom row: spectral index profiles along the minor axis, averaged as done for Fig. 3 (see text Sect. 3.2.2). For all cuts, yellow errors correspond to a flux calibration error of 10% in both bands, while orange errors are estimated from the signal-to-noise in each band. The x-axis corresponds to the offset to the center of the disk in arcseconds.