The Io decametric emission cone

Abstract

The Voyager 1 and 2 Planetary Radio Astronomy observations of Jovian decametric radiation (DAM) were transformed into a fixed Io-Jupiter coordinate system for Io longitudes every 10 deg apart starting from 200 to 260 deg (seven plots per spacecaft). An analysis of the data in this coordinate system has shown that the Io-dependent DAM emissions are generated in hollow cones at all frequencies over the fixed Io longitudes studied. The edges of the emission cones are, in many cases, broad in longitude (30 deg or more), with distinct differences found between the characteristics of DAM emission at the edges of the emission cones. The shapes of the DAM emission cones are explained by using three-dimensional ray-tracing calculations within a model Jovian atmosphere.