Abstract
Isolated magnetic white dwarfs have field strengths ranging from kilogauss to
gigagauss. However, the origin of the magnetic field has not been hitherto
elucidated. Whether these fields are fossil, hence the remnants of original
weak magnetic fields amplified during the course of the evolution of their
progenitor stars, or are the result of binary interactions or, finally, they
are produced by other internal physical mechanisms during the cooling of the
white dwarf itself, remains a mystery. At sufficiently low temperatures white
dwarfs crystallize. Upon solidification, phase separation of its main
constituents, 12C and 16O, and of the impurities left by previous evolution
occurs. This process leads to the formation of a Rayleigh-Taylor unstable
liquid mantle on top of a solid core. This convective region, as it occurs in
Solar System planets like the Earth and Jupiter, can produce a dynamo able to
yield magnetic fields of strengths of up to 0.1 MG, thus providing a mechanism
that could explain magnetism in single white dwarfs.
Users
Please
log in to take part in the discussion (add own reviews or comments).