Possible evidence of solar oscillations in the multifrequency spectra of solar radio brightness fluctuations

Abstract

Changes in solar radio brightness temperature were derived at 2.8, 19.3 and 22.2 GHz from the observations of solar radio flux during the total eclipse on February 16, 1980. High resolution MEM spectra of the brightness temperature fluctuations at the three frequencies showed periodicities ranging from 3.5 min to 128 min. Between 3.5 min and 14.6 min there are a number of comparable significant periodicities common to the three operating frequencies. These periodic variations in brightness temperature may be a result of the spatial and/or temporal variations in the solar radio emissions. Under the assumption of spatial variation, the observed periodicities imply scale sizes of radio emission regions in the range 70,000 km to 600,000 km. Results of the spectral analysis of brightness temperature fluctuations derived from the total solar eclipse observations at 2.8 GHz were reported earlier (Alurkar et al., 1983). In this paper the results of similar analysis for 19.3 and 22.2 GHz and compare them with the former.