Optical polarization observations of circumsolar dust during the 1983 solar eclipse

Abstract

It is very difficult to make optical observations from the Earth where the angular distance from the Sun is greater than 3 R_⊙ (where R_⊙ is the angular radius of the Sun) because of the large and uncertain correction for sky radiation. To overcome these difficulties, we have now made optical polarization observations at four wavelengths (5,330 Å, 5,970 Å, 7,200 Å, 8,015 Å) for the outer solar corona at an altitude of 30 km, using a balloon-borne silicon-intensified (SIT) TV camera during the total solar eclipse on 11 June 1983 in Indonesia. As reported here, a polarization excess at an elongation between 4 and 5 R_⊙ (1° and 1.25°) from the Sun in the ecliptic plane was observed at a wavelength of 8,015 Å on the two-dimensional frame. This is interpreted as an enhancement of dust grains distributed in a ring around the Sun approximately in the ecliptic plane.