Sequence of images of Betelgeuse from linear polarization for the 12 dates given in Table 1. For each date the image (relative intensities) on the left represents the blueshifted signals (spot1) which are located on the visible hemisphere; the image on the right represents the redshifted signals (spot2) which are hypothesized to correspond to the opposite hemisphere. The crosses show the positions corresponding to the maxima of P_L. North is up and east is left for all images. The model used is described in Sect. 5.