Abstract
view Abstract Citations References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Spectrum of the Slowly Varying Component of Solar Radio Emission. Swarup, G. ; Kakinuma, T. ; Covington, A. E. ; Harvey, G. A. ; Mullaly, R. F. ; Rome, J. Abstract The characteristics of the slowly varying component of solar radio em ission associated with sunspot groups having areas >500 millionths of the solar hemisphere have been determined by combining high-resolution observations of ten sources obtained at wavelengths of 3.2, 7.5, 9.1, 10.7, and 21 cm. The observations were made with interferometers which are located at Nagoya, Ottawa, Stanford, and Sydney, and which provide fan and pencil shaped beams having widths of about 1 to 3 min of arc. It appears that a strong source of the slowly varying component has a higher value of flux density near 10 cm than at 3 cm or 21 cm. The size has a value of about 2 to 3 min of arc at wavelengths of 3 and 10 cm and about 3 to 4 min of arc at 21 cm. The calculated values of heights show a large scatter, but are of the order of 10 000 to 20 000 km at wavelengths of 3 and 10 cm, and about 40 000 to 90 000 km at 21 cm. The radio emission is circularly polarized, with the degree of polarization being >30% at 3 cm, 10% at 10 cm and ~2% at 21 cm. At 10.7 cm, the radio brightness temperatures of the ten sources range from 1.6 to 3.8X1060K, when it is assumed that the north-south widths of the sources are the same as the measured east-west widths. The temperatures show good correlation with both sunspot areas and magnetic fields. It is found that the observed spectral characteristics are not consistent with simple magneto-ionic theory in which only the effect of electron-ion collisional absorption is considered; resonance absorption at harmonics of the gyromagnetic frequency should also be considered to explain both the flux density spectrum and the polarization (Kakinuma and Swarup, Astrophys. J., November 1962). Publication: The Astronomical Journal Pub Date: 1963 DOI: 10.1086/109133 Bibcode: 1963AJ.....68S..80S full text sources ADS |
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