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Astron. Astrophys. 343, 865-871 (1999)

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Modelling of magnetic fields of CP stars

II. Analysis of longitudinal field, crossover, and quadratic field observations

S. Bagnulo 1, M. Landolfi 2 and M. Landi Degl'Innocenti 3

1 Institut für Astronomie, Universität Wien, Türkenschanzstrasse 17, A-1180 Wien, Austria (bagnulo@astro.univie.ac.at)
2 Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze, Italy (landolfi@arcetri.astro.it)
3 C.N.R., Gruppo Nazionale di Astronomia, Unità di Ricerca di Arcetri, Largo E. Fermi 5, I-50125 Firenze, Italy (mlandi@arcetri.astro.it)

Received 27 July 1998 / Accepted 15 December 1998


In recent years, the introduction and systematic application of new diagnostic techniques has enormously increased the opportunities to investigate magnetic fields of chemically peculiar (CP) stars. To approach the problem of modelling these fields, in previous papers we set up a theory aimed at describing the magnetic configuration due to the superposition of a dipole with an arbitrary quadrupole. The present work is a first application of this theory to spectro-polarimetric observations of Stokes I and V. We have attempted to model nine magnetic CP stars by analysing their curves of longitudinal field, crossover and quadratic field. We found that the classical dipolar model is adequate in only one case, while in six cases it should definitely be ruled out. For two stars a specific dipole plus quadrupole model has been recovered.

Key words: polarization – stars: chemically peculiar – stars: magnetic fields

Send offprint requests to: S. Bagnulo

© European Southern Observatory (ESO) 1999

Online publication: March 1, 1999