Zoom of the north-east edge of M 31. The top left panel shows part of the Herschel 250 μm image as a colour map, while the same image is shown as contour in the other panels (contours are 3 mJy beam^-1, i.e.  ~3.8σ, 30 mJy beam^-1, and 300 mJy beam^-1), superimposed to the H i map at various velocities. The channel velocities are indicated in the bottom left corner of each panel. Structures in the IR identified as A to D (see also Figs. 1 and 5) are indicated in the panels. The other panels show the SPIRE 250 μm image as contours and channel maps from the high-resolution H i datacube as colour map.