Optical spectra from white dwarfs with very strong magnetic fields have features unknown in any normal stars, according to Roger Angel at the University of Arizona. His recent observations suggest that the electronic structure of atoms in the white dwarfs has been substantially altered, by the magnetic field. Magnetic fields of about 100 million G have been measured.
‘Another effect of the magnetic field is to polarize the light coming from the star.’ Angel says, ‘Free electrons in the surface of the new star are forced to move in spirals by the field, and they radiate circularly polarized light that can be readily measured.’ This also occurs when magnetic white dwarfs are found in binary systems where the companion star is trying to expand and matter is spilling over onto the white dwarf. The hot gas leaving the companion is immediately influenced by the magnetic field, and its motion follows the magnetic field lines.