The Fourth Component of the Solar Radio Radiation-the Rapidly Varing Component

After the internal joint observation of the solar maximum activity of the 22 nd Cycle in China and the international joint observation of Flares 22 Program and Max'91 Compaign, our high time-resolution data observed with the fast sampling radiotelescopes at three frequencies (1.42,2.84 and 3.67 GHz) and four frequencies (1.42,2.00,2.84 and 4.00 GHz) respectively, in two periods were processed. It is found that there is the fourth component of the solar radio radiation, i. e. the rapidly varying component (RVC) in the Sun. Ten categories of observational characteristics of the rapidly varying component are confirmed by us. Among them three are of great importance: 1. The superimposed characteristics. As compared with the slowly varying component (SVC) superimposed on the quiet component (QC), the RVC is superimposed on the burst background, 2. The rapidly varying characteristic. As compared with the 11-year period of QC, the 27-day period of SVC and the burst duration of a few hours or a few minutes, the RVC has a short life of a few seconds or a few milliseconds and 3. The high brightness temperature characteristic. As compared with the burst brightness temperature, the RVC has a brightness temperature as high as 1011-1016K. During the joint observations, a great deal of spikes (or the millisecond lives), rapid flutuations (or the subsecond lives) and impulses (or the second lives) were observed by us,but they all are the parts of the fourth component of the solar radio radiation, i. e. the rapidly varying component.