Image of HD100546 from Ardila et al. (2007) (their Fig. 5) with RGB color coding according to R = B-band, G = V-band and B = I-band. The scale bar is 6′′ which for d = 109 pc (Gaia DR1 data release: Gaia Collaboration 2016) amounts to 654 AU. The image shows the disk in the center out to at least 300 AU, and a much fainter, much larger arc-shaped envelope out to 1000 AU going from south, via south-west to north-west (a dashed line was added to the image to indicate its position, as it is rather faint). Image used with permission of the authors of the referenced paper.