Overlay of the ALMA 3.5 mm continuum emission (white contours) on the 1.4 mm continuum emission (colors) toward cores NE and Main in G31. The white contours are 3, 6, 10, 15, 20, 30, and 40 times 1σ, which is 0.16 mJy beam⁻¹. The 1.4 mm and 3.5 mm synthesized beams are shown in the lower left and right corner, respectively. The names of the sources in which the emission of the Main core has been resolved (see Sect. 3.1 and Table 2) are indicated. Dashed black lines indicate the direction of the E–W and N–S outflows mapped in SiO by B18.