Comparison between a low-excitation SO N_J = 8₈−7₇ line observed using ALMA and the polarized light observed using ZIMPOL. The SO N_J = 8₈−7₇ integrated line intensity was normalized to the peak value in the image and is shown by the colour scale. The red contour shows the 10% level of the SO emission, and represents the edge of the emission region. The white contours show the 1.5, 2.3, and 3.1% levels of the polarization degree observed using ZIMPOL and filters NR, λ_C = 0.65 μm (top panel), and cnt820, λ_C = 0.82 μm (bottom panel). The white and red ellipses on the lower right corner show, respectively, the FWHM of the observed PSF reference star at the given filter in the visible and the beam of the ALMA observations. The offsets in declination and right ascension are given with respect to the position of Mira A.