Zodiacal Light in the Solar Corona.

Abstract

The observations of Grotrian and Ohman show that the continuous light of the corona consists of two components: a component K, strongly polarized and showing no Fraunhofer lines, and a component F, unpolarized and having unbroadened Fraunhofer lines. The former component is believed to arise from electron scattering; the latter is the subject of this paper. An analysis of the photometric data on the corona and on the zodiacal light indicates that the F-com- ponent dominates in the outer corona and suggests strongly that this component is just the extension of the zodiacal light. Other suggested explanations seem to be insufficient. A theory of the scattering in interplanetary space is given. The scattering by a solid particle consists of diffraction and reflection; the first and the most important part has been neglected in earlier discus- sion. Curves of the surface brightness as a function of the elongation are obtained for particles of various sizes on the assumption of a constant space density. The assumption that there are no particles within 0.1 A.U. from the sun changes the results only slightly. Theory and observations are then combined to give the distribution function of the radii, a. It has the form n(a) = 3.5 X 1O~°a~6