Central polarization in our sample. For each target, the Q_ϕ image is corrected for the instrumental polarization but not corrected for the stellar polarization. The brown line with empty circles is perpendicular to the polarization direction, while the percentage in the top right corner indicates the degree of polarization. Where it is known, the position angle of the outer disk is indicated by the blue line with filled squares. The misalignment between the two orientations is expressed in the bottom right corner. Targets are sorted as in Table 1 with the three rows hosting numbers 1−7, 8−14, and 15−21.