Coronal polarization and intensity at the November 12, 1966 Solar Eclipse

Abstract

The 1966 Douglas Solar Eclipse Expedition obtained photographic records of the intensity and polarization of the solar corona on November 12, from a site at Chiguata, Peru. The present paper amplifies a preliminary account in a special publication (Proceedings: Eclipse Symposium, Sao Jose dos Campos, February 5–9, 1968, in press). Here we shall give a more complete description of the equipment, its calibration, methods of reduction, and the results obtained. We compare the observed intensities and polarizations with those predicted by van de Hulst and point out structure indicated by the polarization data. These observations reveal the existence of complicated structures with intensities and polarizations both higher and lower than required by the van de Hulst model. In general high intensities correlate with high polarizations and low intensities with low polarization. However, some instances occur where seemingly normal intensities are associated with lower polarizations and low intensities with high polarizations. We account for these discrepancies in terms of electron concentrations along the line of sight, which do not occur in the simplified model corona. Further, we suggest that the existence of structure, such as streamers, rays, and so on, in the outer corona indicates that the current models tend to underestimate the importance of the K corona in this region.