The plane of polarization of the solar coronal emission on August 11, 1999

A two-dimensional polarization image of the inner regions of the solar coro na (R less than or equal to 1.5R(circle dot)) during the total solar eclips e of August 11, 1999 is presented. This image clearly exhibits both small- and large-scale structure in the distribution of deviations of the plane of polarization from its theoretical direction for coronal emission in the ne ar infrared (570-800 nm). An accuracy for the deviation angles of less than or equal to1 degrees was achieved by reducing the instrumental scattered l ight in the telescope, installing a continuously rotating polaroid near the image plane of the entrance pupil (i.e., the Lyot stop plane), and develop ing a special algorithm for constructing the polarization images based on t he IDL software, in which the properties of the light are described in term s of the Stokes parameters. This algorithm was used to process 24 digitized polarization images of the corona, corresponding to one complete rotation of the polaroid. Analysis of the polarization image for angles of 0 degrees -5 degrees indicates the existence of significant deviations in the inner corona. The polar and equatorial coronal regions are characterized by diffu se and almost uniform structure of the deviation angles, 0.5 degrees +/- 0. 5 degrees, corresponding to Thomson scattering of the photospheric radiatio n by free electrons. Four large-scale structures over the NE, SE, NW, and S W limbs covering about 60 degrees in position angle have deviations of 1 de grees -3 degrees. Numerous small-scale structures with dimensions up to 30 " and deviation angles of 3 degrees -5 degrees tracing strongly curved coro nal streamers were detected in active coronal regions, especially over the NE limb. Interpretation of these deviations in terms of flows of moving ele ctrons implies tangential velocities of up to 2.5 x 10(4) km/s, i.e., elect ron energies of up to 2 x 10(3) eV. (C) 2001 MAIK "Nauka/Interperiodica".