ALMA Band 3 (100 GHz) continuum emission of M512 with [3, 7, 100]σ contours overplotted in white (left). ALMA Band 6 (230 GHz) with [3, 10, 100]σ contours overplotted in white (center). The spectral index as measured from Eq. (1) using only pixels with flux above the 3σ noise level (right). The x- and y-axes report the offset from the central source in arcseconds. The color bars represent the flux density (mJy beam⁻¹) for the ALMA observations (left, center) and the value of the spectral index (right). The images have been created applying a uv taper to the visibilities, with Briggs weighting and robust = 1. Then we have smoothed them to the same resolution of 1″.6, which is roughly the width of the extended emission. The beam is reported in the lower left corner.