Electropolarimetry of the Solar Corona

Abstract

The results of the white-light polarization measurements performed during the solar eclipse of November 3, 1994 are presented. An electropolarimeter of original design controlled by PC had been constructed. It allows us to scan the solar corona during the totality phase of a solar eclipse over 10 concentric rings up to 4 solar radii. In each ring measurements of the total radiation of the solar corona were made at 90 positions with subsequent calculation of polarization degree and direction of plane of polarization. In this way measurements of polarization degree in the inner and outer corona have been carried out. The assumption of an isothermal corona with a hydrostatic distribution of density is used to calculate the polarized components, ln(Kt+/- Kr). The comparison of the observed data with the theoretical curves has shown that density distribution at distances r < (1.2-2.5) Rsunfits the applied corona model. It was found that the temperature in the middle corona in the equatorial zones is constant and equals to 1.53 times 106K, and the density (the parameter of hydrostatic law) varies from 8.2 times 108cm-3(East coronal streamer) to 4.2 times108cm-3(West coronal streamer).