Observation of the polarization of solar radio bursts at 200 Mc/sec.

Abstract

view Abstract Citations (1) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Observation of the polarization of solar radio bursts at 200 Mc/sec. Hatanaka, T. ; Suzuki, S. ; Tsuchiya, A. Abstract While working at Cornell University during 1952-53, it was found out by one of us that the solar radio bursts were almost linearly polarized when the source was very close to the limb of the sun's disk (Hatanaka 1953). The necessity was then discussed for a new type of polarimeter which gives simultaneously at least four independent pieces of information on the polarization. A radio polarimeter has been built since at the Tokyo Astronomical Observatory, University of Tokyo. With a pair of crossed dipoles attached at the focus of a io-meter paraboloid of equatorial mounting and suitable combinations of retardations, it gives six components of polarization, two circular and four linear, almost simultaneously by electronic switching. One set of observations is obtained in 1/200 second. A preliminary analysis (Hatanaka et al. 1955) of the observations made at Tokyo during December 1954 and January 1955, reveals the following facts on the polarization of the so-called polarized bursts: (i) The radiation is a mixture of two components: one is elliptically polarized and the other random. (2) The ellipticity varies from nearly 100 per cent to 10 per cent. The variation from day to day is similar to that of the ellipticity of a circle put tangentially on the sun S surface at the position of the source and viewed from the earth. (3) The degree of polarization, or the fraction of the elliptically polarized component, is more than 90 per cent on most days, but sometimes drops below 50 and even down to 10 per cent. This variation is not well correlated with the position of the source on the sun's disk. It is suggested that the degree of randomness might be associated with the non-iso- tropic nature of the magnetic field in the solar atmosphere where these bursts are emitted. (4) The tilt angle of the ellipse is almost constant during the observing time in a day, but is different on different days. It is pointed out that the direction of the polarization ellipse is rotated by some amount because of the Faraday effect in the earth's ionosphere. The observing frequency is 200 Mc/sec, both at Cornell and Tokyo. Hatanaka, T. `953, Research Report EE-179, Cornell Univ. Hatanaka, T., Suzuki, S. and Tsuchiya, A. `955, Proc. Japan Acad. 31, 8i also Publ. Astr. Soc. Japan, in press. School of Electrical Engineering, Cornell University, Ithaca, N. Y.' and Tokyo Astronomical Observatory, University of Tokyo, Mitaka, Tokyo. Publication: The Astronomical Journal Pub Date: 1955 DOI: 10.1086/107130 Bibcode: 1955AJ.....60Q.162H full text sources ADS |