Radial profile from Herschel 250 μm emission. The mean flux contained in annuii of increasing radius is plotted, normalised against the peak value. The annuii are defined outwards from the centre of the M0.8–0.2 ring ($l=0_{\cdot }^{\circ }804$ and $b=-0_{\cdot }^{\circ }184$) with a thickness of one pixel. The overlaid vertical grey lines define the radii between which the normalised mean flux is above the threshold of 0.5, indicated by the horizontal grey line.