Stokes profile analysis and vector magnetic fields. V. The magnetic field structure of large sunspots observed with Stokes II

Results are presented on the analysis of Stokes II polarimeter data on four large sunspots during 1980, yielding the vector magnetic field structure and thermodynamic parameters of these sunspots. It is found that the magnetic field occupies significant fractions of the area in both light and dark penumbral filaments, and that the intrinsic field does not fall below 600 G, either in the sunspot or in the surrounding plage areas, and is typically 700-800 G at the outer edge of the penumbra. The radial variation of the vector field in these sunspots does not agree with the return-flux models of Fla et al. (1982). The variation of the poloidal field strength and inclination with distance from the center of the symmetric sunspots exhibits little nonpotential character and is well represented by the potential field of a buried dipole. 37 refs