Polarization of the solar corona in the green line: Contradiction between theory and observations

The main results of polarization observations in the 530.3-nm line and thei r role in studying the physical conditions, structure, and magnetic held in the solar corona are discussed. A serious discrepancy between the observat ions and widely-accepted theoretical concepts was revealed: the theory pred icts that the orientation of the polarization electric vector should be nea rly radial, in contradiction with the observational results. In particular, the polarization vectors for both the green line and white-light corona in high-latitude streamers were tangential during the eclipse of July 11, 199 1. The dependence of the degree of polarization on the angle between the ra dial direction and the magnetic-field vector was calculated without any a p riori assumptions about the configuration of coronal fields. This theoretic al analysis of the polarization-vector orientation for magnetic-dipole emis sion in the green line are in agreement with results obtained previously in other studies. Some ways to resolve the observed discrepancies are discuss ed. (C) 2001 MAIK "Nauka/Interperiodica".