Stacked maps of Stokes I (left) and V (right) from LOFAR at 144 MHz for protostellar (top) and prestellar (bottom) cores in the Perseus molecular cloud. The synthetized beam of 20″ FWHM is shown with a white circle in the top left panel. The central region where the mean stacking is performed is shown in all panels by the black circle at the center, which is twice the size of the FWHM. At the distance of Perseus (~300 pc), 90″ corresponds to ~0.15 pc.