view Abstract Citations References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS On the interpretation of the Fraunhofer component of the solar corona. Donn, Bertram Abstract The discovery by Moore and Grotrian in 1934 of unwidened absorption lines in the spectrum of the outer corona together with observations of intensity distribution and polarization have led to the current view that the corona consists of two components. One has a continuous spectrum and arises from electron scattering. The second, which is of interest here, is the Fraunhofer component, containing the absorption lines. Previous workers have shown that the F component must be caused by scattering by solid particles, with diffraction as the dominant process. The interpretation of the F component, therefore, provides an invaluable means of studying the nature of the interplanetary medium. If we describe the scattering cloud by a distribution law for radii, j-V, space density law, ~-~, density of particles at I a.u., NE, minimum and maximum radii, ami and amax, and albedo, ~, the problem is to find the set of values for the parameters which will reproduce the observed coronal characteristics. As a result of the present general investigation, the available data do not seem sufficient to provide a definite answer and the program has turned to finding the restrictions which are placed on the possible solutions for the parameters. A particular set of values which has been found to give fair agreement is p = 2, q = I, amax = 0.01. This is to be compared with Allen's result for the special case a = cm. for which q = I and Van de Hulst's solution for the case q = 0, where p = 2.6 and amax> 0.04 cm. Thus we can conclude that diffraction by a cloud of small particles will account for the F component, and reflection at large elongations will take care of the zodiacal light. However, the observations are too limited spatially and with respect to wave length to give a definite result for the properties of the cloud. This should be considered in any investigation requiring a knowledge of the properties of the interplanetary medium. The possibility of extending the observations especially with infra-red sensitive photographic and photoelectric equipment holds out hope of obtaining a better description of the cloud of particles. Harvard College Observatory, Cambridge, Mass. Publication: The Astronomical Journal Pub Date: 1948 DOI: 10.1086/106151 Bibcode: 1948AJ.....54Q..34D full text sources ADS |