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Zeeman tomography of magnetic white dwarfs. II, The quadrupole-dominated magnetic field of HE 1045-0908
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Euchner, F., Reinsch, K. (Klaus), Jordan, S. (Stefan), Beuermann, K. (Klaus) and Gänsicke, B. T. (Boris T.). (2005) Zeeman tomography of magnetic white dwarfs. II, The quadrupole-dominated magnetic field of HE 1045-0908. Astronomy & Astrophysics, Vol.442 (No.2). pp. 651-660. ISSN 0004-6361
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Official URL: http://dx.doi.org/10.1051/0004-6361:20053038
Abstract
We report time-resolved optical flux and circular polarization spectroscopy of the magnetic DA white dwarf HE 1045−0908 obtained with FORS1 at the ESO VLT. Considering published results, we estimate a likely rotational period of P rot 2.7 h, but cannot exclude values as high as about 9 h. Our detailed Zeeman tomographic analysis reveals a field structure which is dominated by a quadrupole and contains additional dipole and octupole contributions, and which does not depend strongly on the assumed value of the period. A good fit to the Zeeman flux and polarization spectra is obtained if all field components are centred and inclinations of their magnetic axes with respect to each other are allowed for. The fit can be slightly improved if an offset from the centre of the star is included. The prevailing surface field strength is 16 MG, but values between 10 and ∼ 75 MG do occur. We derive an effective photospheric temperature of HE 1045−0908 of T eff = 10 000 ± 1000 K. The tomographic code makes use of an extensive database of pre-computed Zeeman spectra (Paper I).
| Item Type: | Journal Article |
|---|---|
| Subjects: | Q Science > QB Astronomy |
| Divisions: | Faculty of Science > Physics |
| Library of Congress Subject Headings (LCSH): | White dwarf stars, Magnetic stars, Stars -- Atmospheres |
| Journal or Publication Title: | Astronomy & Astrophysics |
| Publisher: | EDP Sciences |
| ISSN: | 0004-6361 |
| Date: | November 2005 |
| Volume: | Vol.442 |
| Number: | No.2 |
| Page Range: | pp. 651-660 |
| Identification Number: | 10.1051/0004-6361:20053038 |
| Status: | Peer Reviewed |
| Access rights to Published version: | Open Access |
| Funder: | Germany. Bundesministerium für Bildung und Forschung (BMBF), Deutsche Forschungsanstalt für Luft- und Raumfahrt (DLR), Particle Physics and Astronomy Research Council (Great Britain) (PPARC) |
| Grant number: | 50OR9903 6 (BMBF/DLR) |
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| URI: | http://wrap.warwick.ac.uk/id/eprint/3581 |
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