Die Verteilung der Röntgenstrahlung der Sonnenkorona über die emittierende Fläche und die Restintensität bei totalen Sonnenfinsternissen

Abstract

In the interpretation of the time changes of the electron density in the E-layer during total eclipses, it has usually been assumed that the intensity of the ionizing radiation is proportional to the area of the optically visible solar disk. Recently, however, it was found that a residual amount ΔJ of the intensity J remains. It is probable that the formation of the E-layer is mainly due to a long-wave X-ray radiation of the corona. The distribution of that radiation over the emitting area of the undisturbed corona is studied in this paper, taking into account the self-absorption of these lines. A brightening near the edge is found. Therefore the value of R = ΔJ J depends on the ratio η of the apparent lunar radius to the solar radius, which may differ appreciably from one eclipse to the other. Because of the ellipticity of the corona, the radiation comes mainly from the equatorial region. Using Wahrmeier's model for the density distribution of the electrons, for the residual radiation R one finds, with η = 1·02 (valid for the eclipses of 1952 and 1954), about 17–22 per cent, with η = 1·06 (eclipse of 1955) about 10–12 per cent. These results may be used for an interpretation of the ionospheric observations; if necessary, the contributions of local sources will have to be taken into account also.