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Application of the Dipole Model to Selected Magnetic White Dwarfs

Published online by Cambridge University Press:  25 April 2016

N. Achilleos  and
D. T. Wickramasinghe
N. Achilleos
Affiliation:
Mt. Stromlo and Siding Spring Observatories, Australian National University
D. T. Wickramasinghe
Affiliation:
Dept. of Mathematics Australian National University
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Abstract

Various authors have reported observations of the flux and circular polarization for the three stars PG 1658 + 441, PG 1533 − 057 and K 813 − 14. On the basis of the observational data, the stars were classified as magnetic white dwarfs. To place constraints on the magnetic field strengths and geometries of these stars, the relevant authors qualitatively compared the data with available theory and, in two cases, used a model of optically thin hydrogen threaded by a magnetic field.

In this paper we use a more detailed model for magnetic white dwarfs to assess the results previously obtained for these three stars. We find that, in two cases, the observed spectra can be explained by the Zeeman splitting of hydrogen lines in a stellar magnetic field which takes the form of a dipole situated at the centre of the star. The circular polarization data for PG 1658 + 441, however, may indicate a field geometry for this star which is significally different from that of a centred dipole.

Type
Stellar
Information
Publications of the Astronomical Society of Australia , Volume 8 , Issue 2 , 1989 , pp. 148 - 153
Copyright
Copyright © Astronomical Society of Australia 1989

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