Ratio (ℛ) between the mean of Stokes I within the central region (black circle in Fig. 3) and the RMS value of Stokes V in the outer region (see top panels), for prestellar (right) and protostellar (left) cores. ℛ is shown as a function of the RA coordinate of each core. The selected sources correspond to ℛ values greater than 2 (black dots above the dashed blue line) and 3 (red dots above the dashed red line).