view Abstract Citations References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Characteristics of Type III Bursts. Malville, J. M. Abstract Observations of the drift rate, 4uration, and frequency range of type III bursts between 5~0-8 Me/sec are discussed. The drift rate below 40 Me/sec is systematically lower than expected from the interferometric measurements in the 60~5 Me/sec range. A lower density gradient than that of Newkirk's streamer model is indicated. The upper frequencies of simultaneous noise storms and type III bursts generally coincide. The two phenomena may be similar, differing primarily in the growth rate of the instabilities. The duration of type III bursts can be related to the electron-proton collision time in the corona. An observed mean duration of 5 see at 25 Me/sec indicates a temperature of 2.7 X 106 0K. It should be possible to test models of the temperature and density structure of the outer corona by observations of type III bursts at very low frequencies. On the basis of Chamberlain's hydrodynamic model of the corona (Astrophys. J. 133, 675, 1961), the duration and bandwidth of type III bursts are predicted down to a plasma frequency of 700 ke/sec. Landau damping appears to be of little significance for type III bursts. The natural bandwidth of the oscillations may be so small that the Landau damping rate is negligible compared to the collision frequency. Electron scattering may be more important than Landau damping for establishing a minimum drift rate for the bursts. Publication: The Astronomical Journal Pub Date: March 1962 DOI: 10.1086/108821 Bibcode: 1962AJ.....67Q.276M full text sources ADS |