Figure 1.

Map of the λ 1.2-mm emission of NGC 4631, overlaid on an image taken from the Digital Sky Survey. The levels are −6 (dotted), 6, 11, 21, 41, and 81 mJy/beam. Only significant emission is shown, and the outer parts of the map with higher noise have been cut off. The small object north of the disk is the dwarf elliptical galaxy NGC 4627; the other companion, NGC 4656, is situated about half a degree away in the southeast.