Investigations on Type III/V Bursts of Solar Radio Emission. Part I: Phenomenology and Properties of Type V Bursts

The phenomenological features of type V radiation are discussed at the basis of fine structure records taken at the Astrophysical Observatory Potsdam since 1958. A phenomenological subclassification is derived from the various forms of appearance. It is believed that significant qualities are only the longer duration than that of normal type III bursts and the fact that nearly always a type III burst is preceding. It seems that there are no urgent reasons to consider type V emission as continuum radiation. It is assumed that no different excitation mechanism is effective for type III and type V. The observational facts are tentatively explainable by special assumptions about the structure of the exciting electron stream. Additionally it is taken into consideration that the prolonged duration of type V is due to a merging process. It is suggested that merging occurs if the same coronal area is reexcited by a second electron stream, whereas superposition occurs if different areas are excited by both the streams. The possibility is considered that harmonics partly contribute to the observed features.