A Study of the Outer Corona from a High Altitude Aircraft at the Eclipse of 1954 June 30: II. Electron Densities in the Outer Corona and Zodiacal Light Regions

Abstract

Data on the brightness and polarization of the solar corona given in a previous paper are analysed to separate the F and K components and to give the electron density in the outer corona and inner zodiacal light regions. The electron density is supposed to be a continuous function of distance from the Sun with a sharp cut-off at a variable position corresponding to a sudden decrease of ionization. Let $$p_{\theta}^{F}$$ be the polarization of the F component at elongation θ. The following results are demonstrated. (1) If no cut-off is assumed and $${p}_{{35^{\circ}}}^{F}\,=0$$, then $$p_{\theta}^{F}\,\lt\,0\, \text{for}\,\theta\,\gt\,{35}^{^{\circ}}$$. But if $${p}_{{35^{\circ}}}^{F}$$ is sufficiently large and positive, $$p_{\theta}^{F}\,\gt\,0$$ for all θ. (2) If a cut-off is imposed just inside the orbit of the earth and $${p}_{{35^{\circ}}}^{F}\,=0$$, then $$p_{\theta}^{F}\,\gt\,0$$ for $$\theta\,\gt\,{35}^{\circ}$$. The relation between the zodiacal light and the corona is discussed. It is shown that there is probably a sharp change of electron density gradient near a position 30R⊙. from the Sun.