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Magnetic field evolution in white dwarfs: The hall effect and complexity of the fieldWe calculate the evolution of the magnetic fields in white dwarfs, taking into account the Hall effect. Because this effect depends nonlinearly upon the magnetic field strength B, the time dependences of the various multipole field components are coupled. The evolution of the field is thus significantly more complicated than has been indicated by previous investigations. Our calculations employ recent white dwarf evolutionary sequences computed for stars with masses 0.4, 0.6, 0.8, and 1.0 solar mass. We show that in the presence of a strong (up to approximately 10(exp 9) G) internal toroidal magnetic field; the evolution of even the lowest order poloidal modes can be substantially changed by the Hall effect. As an example, we compute the evolution of an initially weak quadrupole component, which we take arbitrarily to be approximately 0.1%-1% of the strength of a dominant dipole field. We find that coupling provided by the Hall effect can produce growth of the ratio of the quadrupole to the dipole component of the surface value of the magnetic field strength by more than a factor of 10 over the 10(exp 9) to 10(exp 10) year cooling lifetime of the white dwarf. Some consequences of these results for the process of magnetic-field evolution in white dwarfs are briefly discussed.
Document ID
19950046455
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Muslimov, A. G.
(Univ. of Rochester, Rochester, NY United States)
Van Horn, H. M.
(Univ. of Rochester, Rochester, NY United States)
Wood, M. A.
(Florida Institute of Technology, Melbourne, FL United States)
Date Acquired
August 16, 2013
Publication Date
April 1, 1995
Publication Information
Publication: Astrophysical Journal
Volume: 442
Issue: 2 Pa
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
95A78054
Funding Number(s)
CONTRACT_GRANT: NAGW-2444
CONTRACT_GRANT: NSF AST-92-17988
CONTRACT_GRANT: NSF AST-91-15132
Distribution Limits
Public
Copyright
Other

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