Hostname: page-component-78c5997874-8bhkd Total loading time: 0 Render date: 2024-11-14T23:34:04.568Z Has data issue: false hasContentIssue false
  • English
  • Français

Opacities in Strong Magnetic Helds

Published online by Cambridge University Press:  30 March 2016

Dayal T. Wickramasinghe
Dayal T. Wickramasinghe*
Affiliation:
The Astrophysical Theory Centre, Australian National University, Canberra ACT 2601, Australia

Extract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

White dwarfs are one of the most readily studied end products of stellarevolution. Their observed properties have provided and continue to provide important constraints for the theory of stellar evolution. Likewise, a study of magnetism in white dwarfs provides unique insights into the origin and evolution of magnetic fields in stars.

Spectacular progress has been made on the specific problem of the structure of the hydrogen atom in strong fields. Energy levels and transition probabilities are now known for all low lying states of hydrogen for the entire range of field strengths appropriate to white dwarfs and neutron stars (104-1013G) (Rosner et al 1984, Forster et al 1984 and Henry and O’Connell 1984). These calculations resulted in the identification of spectral features in the magnetic white dwarf Grw+70°8247 which had remained unidentified for over 50 years (Minkowski 1938), with Zeeman shifted hydrogen lines in a magnetic field of 100 -320 MG ((eg Wickamasinghe and Ferrano 1989). Several other strong field magnetic white dwarfs have since been discovered through hydrogen Zeeman spectroscopy. The data presently at hand show that most hydrogen rich magnetic white dwarfs have complex non-dipolar field structures with strong evidence for higher order multipole components.

Type
II. Joint Discussions
Information
Highlights of Astronomy , Volume 10: Highlights of Astronomy. As presented at the XXIInd General Assembly of the IAU, 1994 , 1995 , pp. 588 - 590
Copyright
Copyright © Kluwer 1995

References

Forster, H., Strupat, W., Rosner, W., Wunner, G., Ruder, H. and Herold, H., 1984, J.Phys.B; At. Mol Phys. 17, 1301 CrossRefGoogle Scholar
Henry, R.J.W. and O’Connell, R.F., 1984, ApJ, 282, L28 CrossRefGoogle Scholar
Minkowski, R., 1938, Ann. Rept. Div. Mt. Wilson Obs., 28 Google Scholar
Merani, N., Main, J. and Wunner, G., A&A, in pressGoogle Scholar
Rosner, W., Wunner, G., Herold, H. and Ruder, H., 1984, J. Phys. B.; At. Mol.Phys., 17, 29 CrossRefGoogle Scholar
Thurner, G., Korbel, H. Braun, M., Herold, H., Ruder, H. and Wunner, G., 1993, J. Phys. B.; At. Mol. Opt. Phys., 26, 4719 CrossRefGoogle Scholar
Wickramasinghe, D.T. and Ferrano, L., 1988, ApJ, 327, 222 CrossRefGoogle Scholar