The stellar coordinate system. The Z_*‐axis is the symmetry axis, and the observer views the star along the Z‐axis that is located in the X_*‐Z_* plane. The Y and Y_*‐axes (not shown) are into the page and coincident. The viewing inclination angle, i, is measured from the Z_*‐axis to the Z‐axis. The angles and are the spherical polar angles in the stellar coordinate system. The three arrows labeled n_B, n_i, and n_s are unit vectors for the directions of the magnetic field, incident intensity, and scattered intensity, respectively. The vector r is the spatial position of the scattering point P with respect to the origin.