LSD Stokes V and I profiles for β Hyi derived from HARPSpol observations (top). For illustration purposes, Stokes V is scaled and shifted vertically in relation to Stokes I. The black solid line shows the mean observed profile, with the respective uncertainty indicated by the gray-shaded region. The vertical dotted line marks the line center. The red and blue lines indicate the best-fit models obtained for a dipole field, considering an axisymmetric and an inclined field, respectively. The red squares and blue circles show the corresponding residuals for the Stokes V profile (bottom). The fitting parameters and χ² values are annotated within the panels.