PARAMETERS OF SUNSPOT MAGNETIC-FIELDS AS DETERMINED USING PENUMBRAL STRUCTURE

A field of directions, determined by chromospheric fibriles, was earlier shown to contain information, sufficient for a solution of the boundary-value (Dirichlet's) problem on the B field, if the fibriles' directions on a plane are known. In a number of cases, the field of directions is known only for some ring zones around a spot. This is enough for determination of main integral parameters of the spot's magnetic field. For the observed structures, relative values of the dipole and quadrupole moments as well as the total longitudinal current are obtained. A transition is realized from the field of directions to the envelope of a family of straight lines on a circle. The envelopes demonstrate a low sensitivity to the choice of circles but characterize the field structure with a sufficient completeness. For a number of spots, envelopes of fibriles' tangents in the superpenumbral region are constructed, and the data corresponding to the parameters of spots are obtained. The relative value of the azimuthal component, characterizing the current in a spot, is of the order of 0,2-0,3.