Jovian longitudinal control of Io-related radio emissions.
Abstract
A theoretical model is proposed to explain the control of Io-related radio emissions by Jupiter's rotational phase. The model is based on the hypothesis that the radio emissions are generated by Birkeland currents flowing between Io and the Jovian ionosphere. Specifically, it is suggested that the precipitation of radiation-belt electrons within a certain range of Jovian longitudes produces a restricted region of enhanced ionization and correspondingly enhanced conductivity in Jupiter's ionosphere and that the Io-Jupiter Birkeland current and the associated radio emissions are dramatically increased when Io's flux tube encounters this sector of enhanced ionization in Jupiter's ionosphere. The magnitude of the current is found to be about 100,000 A at most Jovian longitudes because of ionospheric resistance. It is estimated that within the favored longitudinal sector electron precipitation produces an enhancement of this current by one to three orders of magnitude. The model predictions are compared with observations made during the Pioneer 10 and 11 flybys, and satisfactory agreement is obtained.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- January 1979
- DOI:
- 10.1086/156777
- Bibcode:
- 1979ApJ...227..664D
- Keywords:
-
- Io;
- Jupiter Atmosphere;
- Longitudinal Control;
- Planetary Radiation;
- Radio Emission;
- Birkeland Currents;
- Electron Precipitation;
- Gas Ionization;
- Planetary Ionospheres;
- Planetary Magnetospheres;
- Planetary Rotation;
- Lunar and Planetary Exploration;
- Io:Jupiter Ionosphere;
- Jupiter:Radio Radiation