Flattening modulus of a neutron star by rotation and magnetic field
  We calculated the ellipticity of the deformed star due to the rotation or magnetic field. These two effects are compared to each other within general relativity. It turned out that the magnetic distortion is important for recently observed candidates of magnetars, while the magnetic effect can be neglected for well-known typical pulsars. 
K. Konno, T. Obata, Y. Kojima