An equatorially symmetric rotator model for magnetic stars. II. Inhomogeneous element distribution

Abstract

AbstractFor the construction of more realistic models of magnetic stars the influence of large inhomogeneities in the distribution of line absorbing elements over the stellar surface on the determination of the mean longitudinal magnetic field component, Beff, is discussed. In this paper we assume the same magnetic field geometry as in paper I, i.e. the superposition of a dipole and an axissymmetrical quadrupole both lying in the equatorial plane with their axes parallel to one another. The models for the inhomogeneties can be classified by the concentration of the line absorbing elements:(1) at the polar caps, (2) in rings surrounding the polar caps, (3) in a belt in the neighbourhood of the “magnetic” latitude δ = 90°. The result of the computations shows that the amount of compensations of both polarities by integration over the visible hemisphere may be remarkably reduced, yielding values of Beff not so far away from the polar field strength as in the homogeneous models.Moreover, the large quadrupole contribution necessary in some cases to represent the observations in the homogeneous models may be considerably smaller with inhomogeneites taken into account. First comparisons between computed and observed values of Beff(t) are made for the stars α2CVn, 53 Cam and HD 215441.