EDP Sciences
Free access
Issue
A&A
Volume 414, Number 3, February II 2004
Page(s) 1105 - 1108
Section Stellar structure and evolution
DOI http://dx.doi.org/10.1051/0004-6361:20034297


A&A 414, 1105-1108 (2004)
DOI: 10.1051/0004-6361:20034297

HE0241-0155 - Evidence for a large scale homogeneous field in a highly magnetic white dwarf

D. Reimers1, S. Jordan2 and N. Christlieb1

1  Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany
2  Institut für Astronomie und Astrophysik, Eberhard-Karls-Universität Tübingen, Sand 1, 72076 Tübingen, Germany

(Received 10 Septembre 2003 / Accepted 3 November 2003)

Abstract
In the course of the Hamburg/ESO survey we have discovered a white dwarf whose spectrum exhibits many similarities with the prototype of magnetic white dwarfs Grw+70 $^{\circ}$8247. In particular several stationary line components indicative for magnetic fields between about 150 and 400 MG are found in both objects. However, the features between 5000 and 5500 Å in the spectrum of HE0241-0155 cannot be explained by stationary line components and demand a relatively homogeneous magnetic field with clustering around 200 MG. For this reason a pure dipole model failed to reproduce this spectral region. An offset-dipole configuration led to some improvement in the fit but a good agreement was only possible for a geometry - described by an expansion into spherical harmonics - where most of the surface is covered with magnetic field strengths strongly clustered around 200 MG. This may indicate the presence of a large magnetic spot whose presence could be tested with time resolved spectro-polarimetry.


Key words: stars: white dwarfs -- stars: magnetic fields -- radiative transfer -- magnetic fields

Offprint request: D. Reimers, dreimers@hs.uni-hamburg.de

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© ESO 2004