Magnetic deformation of the white dwarf surface structure
(2000) In Astronomische Nachrichten 321(3). p.193206 Abstract
The influence of strong, largescale magnetic fields on the structure and temperature distribution in white dwarf atmospheres is investigated. Magnetic fields may provide an additional component of pressure support, thus possibly inflating the atmosphere compared to the nonmagnetic case. Since the magnetic forces are not isotropic, atmospheric properties may significantly deviate from spherical symmetry. In this paper the magnetohydrostatic equilibrium is calculated numerically in the radial direction for either for small deviations from different assumptions for the poloidal current distribution. We generally find indication that the scale height of the magnetic white dwarf atmosphere enlarges with magnetic field strength and/or... (More)
The influence of strong, largescale magnetic fields on the structure and temperature distribution in white dwarf atmospheres is investigated. Magnetic fields may provide an additional component of pressure support, thus possibly inflating the atmosphere compared to the nonmagnetic case. Since the magnetic forces are not isotropic, atmospheric properties may significantly deviate from spherical symmetry. In this paper the magnetohydrostatic equilibrium is calculated numerically in the radial direction for either for small deviations from different assumptions for the poloidal current distribution. We generally find indication that the scale height of the magnetic white dwarf atmosphere enlarges with magnetic field strength and/or poloidal current strength. This is in qualitative agreement with recent spectropolarimetric observations of Grw+10°8247. Quantitatively, we find for e.g. a mean surface poloidal field strength of 100 MG and a toroidal field strength of 210 MG an increase of scale height by a factor of 10. This is indicating that already a small deviation from the initial forcefree dipolar magnetic field may lead to observable effects. We further propose the method of finite elements for the solution of the twodimensional magnetohydrostatic equilibrium including radiation transport in the diffusive approximation. We present and discuss preliminary solutions, again indicating on an expansion of the magnetized atmosphere.
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 author
 Fendt, Ch and Dravins, D. ^{LU}
 organization
 publishing date
 2000
 type
 Contribution to journal
 publication status
 published
 keywords
 Fundamental parameters, Magnetic fields, Stars: Atmospheres, White dwarfs
 in
 Astronomische Nachrichten
 volume
 321
 issue
 3
 pages
 14 pages
 publisher
 John Wiley & Sons
 external identifiers

 scopus:0034353958
 ISSN
 00046337
 language
 English
 LU publication?
 yes
 id
 aaf670a279444e7dbca4d25566dd3b2f
 date added to LUP
 20171122 15:22:43
 date last changed
 20180529 10:35:03
@article{aaf670a279444e7dbca4d25566dd3b2f, abstract = {<p>The influence of strong, largescale magnetic fields on the structure and temperature distribution in white dwarf atmospheres is investigated. Magnetic fields may provide an additional component of pressure support, thus possibly inflating the atmosphere compared to the nonmagnetic case. Since the magnetic forces are not isotropic, atmospheric properties may significantly deviate from spherical symmetry. In this paper the magnetohydrostatic equilibrium is calculated numerically in the radial direction for either for small deviations from different assumptions for the poloidal current distribution. We generally find indication that the scale height of the magnetic white dwarf atmosphere enlarges with magnetic field strength and/or poloidal current strength. This is in qualitative agreement with recent spectropolarimetric observations of Grw+10°8247. Quantitatively, we find for e.g. a mean surface poloidal field strength of 100 MG and a toroidal field strength of 210 MG an increase of scale height by a factor of 10. This is indicating that already a small deviation from the initial forcefree dipolar magnetic field may lead to observable effects. We further propose the method of finite elements for the solution of the twodimensional magnetohydrostatic equilibrium including radiation transport in the diffusive approximation. We present and discuss preliminary solutions, again indicating on an expansion of the magnetized atmosphere.</p>}, author = {Fendt, Ch and Dravins, D.}, issn = {00046337}, keyword = {Fundamental parameters,Magnetic fields,Stars: Atmospheres,White dwarfs}, language = {eng}, number = {3}, pages = {193206}, publisher = {John Wiley & Sons}, series = {Astronomische Nachrichten}, title = {Magnetic deformation of the white dwarf surface structure}, volume = {321}, year = {2000}, }