Attempt to model the ( Q/ I, U/ I) wing signatures. The observations (dotted lines) shown here correspond to the "magnetic observations" presented in Figure  2. In the Q/ I panel the heavy solid line represents the magnetic model profile, the thin solid line the nonmagnetic model profile, and the dashed line their difference. In the U/ I panel, the solid line represents the magnetic model profile. The parameters used are (Γ _B , _B , _B ; Γ _E/Γ _R) = (10, 90°, 135°; 10).