GREEN-LINE POLARIZATION OBSERVATIONS OF THE SOLAR CORONA AND THEIR INTERPRETATION

Polarization observations in the lambda 5303 Angstrom FeXIV line durin g the eclipse of July 11, 1991 are presented. A new polarization map p robing somewhat greater heights in the corona is constructed, and the distribution of polarization position angles is given. Low degrees of polarization p are obtained ill the equatorial regions; at low heights , they are consistent with the results of out-of-eclipse observations. The values for p ale higher in regions of high-latitude streamers, an d increase substantially with distance from the limb. The method used in the analysis made it possible to separate the line emission into tw o components (associated with excitation due to electron collisions an d with resonant scattering of the photospheric radiation), and also to estimate the density and overall extent of the emitting region. The o bserved values of p ale consistent with current ideas about the corona if the relative density of the FeXIV ion is 2 x 10(-5) and the rate o f excitation by electron collisions is 5 x 10(-9) cm(3)/s. The possibl e role of magnetic fields is briefly discussed.