RADIO EVIDENCE FOR SOLAR CORPUSCULAR EMISSION
Scientific rept. no. 5
HARVARD RADIO ASTRONOMY STATION FORT DAVIS TX
Pagination or Media Count:
This paper reviews the relation of solar radio bursts of spectral type IV to the ejection of relativistic and sub-relativistic solar particles the relation of bursts of types II and IV to the ejection of solar plasma and radar evidence for quiet solar streaming. Ejection of relativistic and sub- relativistic particles by flares is virtually always accompanied by type-IV radio bursts. The minimum Sun-Earth travel time for these particles is about 20 min. Ejection of plasma from flares accompanied by bursts of types II and IV is considered in terms of subsequent geomagnetic effects. Type IV bursts are highly associated with geomagnetic storms and type II bursts have a small but significant association. The Sun-Earth travel time for the storm plasma is generally 36-48 hr. Type II Bursts may possibly be identified with passage through the corona of a large amplitude shock wave, which then propagates outwards through the interplanetary plasma, causing a geomagnetic sudden commencement when it reaches the earth. The presence of type IV radiation may be indicative of the amount of material transported behind the shock front. Radar observations of the solar corona indicate that at a height of approximately 350, 000 km above the photosphere there is a net outward flow of matter at a velocity of about 16 kmsec. This velocity is consistent with Parkers hydrodynamic theory, for coronal temperatures of the order of 10 to the 6th power degrees K.