Mapping Magnetic Fields of CP Stars from Stokes I and V Observations

Abstract

Chemically peculiar (CP) stars of the upper main sequence are distant enough to permit us a relatively simplified approach to the problem of modelling their magnetic morphology. However, new observational techniques recently introduced by Mathys (1993) show that the common assumption of a‘quasi-dipolar’ field is too coarse an oversimplification. Although large-scale organised, the magnetic morphologies of CP stars exhibit a non axisymmetric and rather complex structure, which in some cases can be conveniently described in terms of the superposition of a dipole field and a quadrupole field. As a special example, I present a detailed model of a magnetic CP star, fully consistent with observations of Stokes I and V, Doppler broadening, and stellar radius.