Magnetic field configurations for a dipole with (α_D, φ_D) = (45° ,0° ) and a quadrupole with two different orientations. Left: (α_Q, φ_Q) = (80° ,95° ). Right: (α_Q, φ_Q) = (80° ,180° ). B_Q/B_D = 5 in both cases. The top and middle panels show the angle of the surface magnetic field with respect to the radial direction, cos θ_B, and the relative magnetic field strength at the surface, B/B_D, in Mollweide projection. The maps cover the whole NS surface with latitudes in the range [−90°, 90°] and longitudes in the range [−180°, 180°]. The boundaries of the polar caps are shown with solid black lines. In the 3D representations, we represented closed field lines in blue, open field lines in red. The green arrow indicates the rotation axis of the NS. All distances are scaled by the stellar radius, R^*.