Attempts to measure the magnetic field of the pulsating B star ν Eridani

¹ Astronomical Institute “Anton Pannekoek”, University of Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands e-mail: rschnerr@science.uva.nl
² European Space Astronomy Centre (ESAC), Research & Scientific Support Department of ESA, Villafranca del Castillo, PO Box 50727, 28080 Madrid, Spain
³ Institute for astronomy, KU Leuven, 3001 Leuven, Belgium
⁴ GEPI, UMR 8111 du CNRS, Observatoire de Paris-Meudon, 92195 Meudon Cedex, France

Received: 2 December 2005
Accepted: 7 March 2006

Abstract

We report on attempts to measure the magnetic field of the pulsating B star ν Eridani with the Musicos spectropolarimeter attached to the 2 m telescope at the Pic du Midi, France. This object is one of the most extensively studied stars for pulsation modes, and the existence of a magnetic field was suggested from the inequality of the frequency separations of a triplet in the stars' oscillation spectrum. We show that the inferred 5-10 kG field was not present during our observations, which cover about one year. We discuss the influence of the strong pulsations on the analysis of the magnetic field strength and set an upper limit to the effective longitudinal field strength and to the field strength for a dipolar configuration. We also find that the observed wind line variability is caused by the pulsations.