Low-frequency Jovian emission and solar wind magnetic sector structure

Abstract

The Earth, Jupiter and Saturn emit non-thermal low-frequency radiations with similar characteristics. For the Earth and Saturn, the radio emissions are known to fluctuate with a time scale of several days, correlated with variations of the solar wind or related phenomena at the planet^1–4. Several studies of the jovian radiation at decametre wavelengths, from ground-based observations, suggest that the non-Io-controlled emission fluctuates in response to the sector structure of the interplanetary magnetic field^5–9. We study here the long-term fluctuations of the jovian emission at hectometre and kilometre wavelengths. We use observations from the Planetary Radio Astronomy (PRA) experiment aboard the two Voyager spacecraft. We show that these emissions are strongly affected by the magnetic sector structure at Jupiter. This leads us to discuss the position of the sources of emission in the jovian magneto-sphere.