A common origin of magnetism from planets to white dwarfs
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.
Keywords
Cite
@article{arxiv.1702.01813,
title = {A common origin of magnetism from planets to white dwarfs},
author = {Jordi Isern and Enrique García-Berro and Baybars Külebi and Pablo Lorén-Aguilar},
journal= {arXiv preprint arXiv:1702.01813},
year = {2017}
}
Comments
The Astrophysical Journal Letters, 836:L28 (5pp), 2017 February 20