2000MNRAS.315L..41M

We present Hα spectra of the magnetic white dwarf star WD1953-011 which confirm the presence of the broad Zeeman components corresponding to a field strength of ∼500kG found by Maxted & Marsh. We also find that the line profile is variable over a time-scale of a day or less. The core of the Hα line also shows a narrow Zeeman triplet corresponding to a field strength of ∼100kG which appears to be almost constant in shape. These observations suggest that the magnetic field on WD1953-011 has a complex structure, and that the star has a rotational period of hours or days which causes the observed variability of the spectra. We argue that neither an offset dipole model nor a double-dipole model is sufficient to explain our observations. Instead, we propose a two-component model consisting of a high-field region of magnetic field strength ∼500kG covering about 10per cent of the surface area of the star, superimposed on an underlying dipolar field of mean field strength ∼70kG. Radial velocity measurements of the narrow Zeeman triplet show that the radial velocity is constant to within a few km.s^–1, so this star is unlikely to be a close binary.