Top panel: linearly polarized intensity P (colors) and dust continuum emission map (contours) at 1.3 mm in G31. Polarized intensity ranges from 0.11 to 2.4 mJy beam⁻¹. Bottom panel: polarization fraction p (colors) anddust continuum emission map (contours) at 1.3 mm. Polarization fraction ranges from 0.1 to 13%. The red thick segments in both panels indicate the magnetic field lines. Segments are shown every eight pixels. The synthesized beam is shown in the lower left-hand corner. Contours and symbols are the same as in Fig. 1.