ALMA dust continuum images of SR 21. Band 9 (rms = 3 mJy beam⁻¹) and Band 7 (rms = 0.2 mJy beam⁻¹) were reproduced from Pérez et al. (2014) and Pinilla et al. (2015b), respectively. Our new Band 3 observations (rms = 13.6 μJy beam⁻¹) are shown in the third panel. Beam size and orientation are indicated by the white ellipses in each panel. Right panel: H-band data in the same color scale as Fig. 1, left panel, with the ALMA Band 3 contours at 6, 12, 18, and 24σ overlaid.