Comparison of the radiative interaction (solid lines) and magnetic precession rates (dash-dotted lines) of the investigated molecules toward CW Leo. The magnetic precession rates are given for magnetic fields B = B_surf(R/R_star)^−q, adopting q = 1, q = 2 and 3, where for q = 1 a B_surf = 1 mG was adopted, while for q = 2 and 3, B_surf = 1 G was adopted. The black curve composed of long dashes indicates the expected magnetic precession rates that explain the polarisation morphology of CS, CO, and H¹³CN within 1.4″. The horizontal black dotted and dash-dotted lines indicate the molecular magnetic precession rates at 1 mG and 1 μG, respectively. The vertical black and red dotted lines indicate telescope resolution and the 1.4″ radius where a polarisation morphology change was observed (see Sect. 3.2). The orange coloured region indicates the magnetic field strengths where CO would be aligned to the magnetic field but H¹³CN would be aligned in the radial direction along the stellar radiation field.