Journal article
Direction-finding measurements of type III radio bursts out of the ecliptic plane
Solar physics, Vol.48(2), pp.361-380
06/1976
DOI: 10.1007/BF00152002
Abstract
Direction-finding measurements with the plasma wave experiments on the Hawkeye-1 and IMP-8 satellites are used to find the source locations of type III solar radio bursts in heliocentric latitude and longitude in a frequency range from 31.1 to 500 kHz. IMP-8 has its spin axis perpendicular to the ecliptic plane; hence, by analyzing the spin modulation of the received signals, the location of the type III burst projected into the ecliptic plane can be found. Hawkeye-1 has its spin axis nearly parallel to the ecliptic plane; hence, the location of the source out of the ecliptic plane may also be determined. By using an empirical model for the emission frequency as a function of radial distance from the Sun, the three-dimensional trajectory of the type III radio source can be determined from direction-finding measurements at different frequencies. Since the electrons that produce these radio emissions follow the magnetic field lines from the Sun, these measurements provide information on the three-dimensional structure of the magnetic field in the solar wind. The source locations projected into the ecliptic plane follow an Archimedean spiral. Perpendicular to the ecliptic plane, the source locations usually follow a constant heliocentric latitude. When the best fit magnetic field line through the source locations is extrapolated back to the Sun, this field line usually originates within a few degrees from the solar flare that produced the radio burst. With direction-finding measurements of this type, it is also possible to determine the source size from the modulation factor of the received signals. For a type III event on June 8, 1974, the half angle source size was measured to be similar to 60 deg at 500 kHz and similar to 40 deg at 56.2 kHz as viewed from the Sun.
Details
- Title: Subtitle
- Direction-finding measurements of type III radio bursts out of the ecliptic plane
- Creators
- Mark M Baumback - University of IowaWilliam S Kurth - University of IowaDonald A Gurnett - University of Iowa
- Resource Type
- Journal article
- Publication Details
- Solar physics, Vol.48(2), pp.361-380
- DOI
- 10.1007/BF00152002
- ISSN
- 0038-0938
- eISSN
- 1573-093X
- Language
- English
- Date published
- 06/1976
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984455546802771
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