Volume 390, Number 2, August I 2002
|Page(s)||633 - 647|
|Section||Stellar structure and evolution|
|Published online||12 July 2002|
Zeeman tomography of magnetic white dwarfs
I. Reconstruction of the field geometry from synthetic spectra
Universitäts-Sternwarte Göttingen, Geismarlandstr. 11, 37083 Göttingen, Germany
2 Institut für Astronomie und Astrophysik, Universität Kiel, 24098 Kiel, Germany
3 Institut für Astronomie und Astrophysik, Universität Tübingen, Sand 1, 72076 Tübingen, Germany
Corresponding author: F. Euchner, firstname.lastname@example.org
Accepted: 15 May 2002
We have computed optical Zeeman spectra of magnetic white dwarfs for field strengths between 10 and 200 MG and effective temperatures between 8000 and 40 000 K. They form a database containing 20 628 sets of flux and circular polarization spectra. A least-squares optimization code based on an evolutionary strategy can recover relatively complex magnetic field topologies from phase-resolved synthetic Zeeman spectra of rotating magnetic white dwarfs. We consider dipole and quadrupole components which are non-aligned and shifted off-centre. The model geometries include stars with a single high-field spot and with two spots separated by ~90°. The accuracy of the recovered field structure increases with the signal-to-noise ratio of the input spectra and is significantly improved if circular polarization spectra are included in addition to flux spectra. We discuss the strategies proposed so far to unravel the field geometries of magnetic white dwarfs.
Key words: white dwarfs / stars: magnetic fields / stars: atmospheres / polarization
© ESO, 2002
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.