ALMA 342 GHz continuum (blue contours) overplotted on Spitzer 4.5 μm image. The contours are logarithmically spaced, with the first contour at 2 mJy and the tenth and last contour at 200 mJy. The ALMA data are not primary-beam corrected, making the sources far from the phase centre at IRS7B appear fainter than they are. The dashed box shows the coverage of the moment maps in Fig. 3.