Rapidly Rotating Stars.IV. Magnetic White Dwarfs

The self-consistent-field method of determining the equilibrium structure of a non-spherical star is extended to include an internal magnetic field. Models of white-dwarf stars are constructed that are uniformly rotating and contain fields that vanish at the surface. For the particular field configuration chosen, it is found that moderate internal fields can significantly increase the radii of white dwarfs while leaving their surface regions nearly spherical. This provides an explanation for the observations that the radii of Sirius B, 40 En B, and a sample of white dwarfs investigated by Greenstein and Trimble are apparently somewhat larger than predicted by the classical mass-radius relations