Fine structure and time variation of the quiet Sun at 1.3 cm

Abstract

The Hat Creek two-element interferometer has been used to study the quiet Sun at 22 GHz. A statistical analysis of output of the interferometer clearly shows the existence of time variations on the quiet Sun with time scales ˜180 s. The observations suggest that the fine structure on the quiet Sun might consist of two components - one which varies with the time scales ˜3 min and the other being relatively stable. The average visibility amplitude indicates that the fine structure on the Sun has a typical angular size of ˜6". The observation that the variance and the mean of the visibility amplitudes depend in the same way on the projected baseline suggests that the transient sources have angular size similar to the average size of the fine structure on the quiet Sun. Power spectra of the output of the interferometer show no significant periodicity.