The Position and Movement on the Solar Disk of Sources of Radiation at a Frequency of 97 Mc/s. II. Noise Storms

Abstract

Using the equipment described in Part I of this series, the apparent position and polarization of the sources of solar radiation at 97 Mc/s have been measured at some time during about 30 noise storms occurring between May 1949 and July 1950, and the progress of the source daring about six of these has been observed in some detail. The best criterion available for the chance of a storm occurring is shown to be the size of the largest visible individual sunspot. The evidence suggests that the storm radiation is associated with this spot only and not with the rest of the group, that the spot magnetic field is the important factor, and that the direction of rotation of the circular polarization of the storm radiation depends on the magnetic polarity of the associated spot, being usually left-handed when the largest spot is a north-seeking pole and right-handed when it is a south pole. Deviations observed between the apparent positions of radio source and visible sunspot on the solar disk are explained in terms of a high origin of the storm radiation in the solar corona, the observed heights varying from 0.3 to 1.0 photospheric radii above the Sun's visible surface.