Spectral Observations of Solar Radio Bursts. II. Slow-Drift Bursts and Coronal Streamers.

The characteristic properties of slow-drift bursts are summarized: occurrence, duration, frequency range, harmonics, band-splitting, association with flares and other radio bursts. Analysis of the experimental data suggests that the bursts are caused by a disturbance being propagated along a coronal streamer in which the electron density is approximately 10 times that of the Baumbach-AIlen model corona. The radial velocity of this disturbance, deduced from a detailed examination of the frequency drift of the bursts, is estimated as km/sec. Some unexplained characteristics of slow-drift bursts, notably their limited frequency range and the absence of third and higher harmonics, are discussed.