Top row: intensity images I, with a square root gray scale from minimum to maximum intensity (in W m^-2 μm^-1 sr^-1). The dashed red circle represents the size of the photosphere in the near-infrared (R_⋆). The beam size (FWHM of the PSF star images) is shown as a white ellipse in the lower left corner. Bottom row: maps of the degree of linear polarization p_L, with a linear color scale from 0 to 12% (identical for all maps). The field of view is 302 × 302 mas, and all frames have been deconvolved using IRAF’s lucy algorithm (80 steps).