Magnetic deformation of the white dwarf surface structure
Fendt, Ch and Dravins, D. LU
(2000)
In Astronomical Notes - Astronomische Nachrichten
321(3).
p.193-206
- Abstract
The influence of strong, large-scale 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 non-magnetic 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, large-scale 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 non-magnetic 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 2-10 MG an increase of scale height by a factor of 10. This is indicating that already a small deviation from the initial force-free dipolar magnetic field may lead to observable effects. We further propose the method of finite elements for the solution of the two-dimensional magnetohydrostatic equilibrium including radiation transport in the diffusive approximation. We present and discuss preliminary solutions, again indicating on an expansion of the magnetized atmosphere.
(Less)
- 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
- Astronomical Notes - Astronomische Nachrichten
- volume
- 321
- issue
- 3
- pages
- 14 pages
- publisher
- John Wiley & Sons Inc.
- external identifiers
-
- scopus:0034353958
- ISSN
- 0004-6337
- language
- English
- LU publication?
- yes
- id
- aaf670a2-7944-4e7d-bca4-d25566dd3b2f
- date added to LUP
- 2017-11-22 15:22:43
- date last changed
- 2024-01-14 10:38:01
@article{aaf670a2-7944-4e7d-bca4-d25566dd3b2f,
abstract = {{<p>The influence of strong, large-scale 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 non-magnetic 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 2-10 MG an increase of scale height by a factor of 10. This is indicating that already a small deviation from the initial force-free dipolar magnetic field may lead to observable effects. We further propose the method of finite elements for the solution of the two-dimensional 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 = {{0004-6337}},
keywords = {{Fundamental parameters; Magnetic fields; Stars: Atmospheres; White dwarfs}},
language = {{eng}},
number = {{3}},
pages = {{193--206}},
publisher = {{John Wiley & Sons Inc.}},
series = {{Astronomical Notes - Astronomische Nachrichten}},
title = {{Magnetic deformation of the white dwarf surface structure}},
volume = {{321}},
year = {{2000}},
}