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Jupiter

The planet Jupiter has been an object of interest since antiquity. In the 17th century Galileo discovered the large moons, named by Cassini for the various lovers of Zeus in Greek mythology including Io and Ganymede). In 1962, the modulation of the Jovian decametric radiation by Io was discovered, in 1975, Yuri Mekler, Irena Kupo and I found the cold Io plasma torus from the ground and 1979 the phenomenal volcanic activity of Io was observed for the first time by Voyager 1 along with the observations of the hot plasma torus by the PLS team and the ultraviolet instrument. Since then, the Jovian system has been the subject of intense research and I have had the privilege of making some small contribution to it.

Our early Jupiter studies at TAU , the Ph.D. dissertation work of Ron Schreier, were focused primarily on the outer part of the Io torus and its interface with the mid- magnetosphere plasma, i.e. we considered the region between the planetocentric radial distances of 7 to 20 . This region is of great interest since it contains the sharp gradient in flux tube content region where precipitation of particles into the atmosphere to create the aurora takes place. The urgent question resolved in this region, with the aid of the data analysis and theoretical modeling in our group, is the establishment of the roles of the various components of the plasma. The significance of this determination lies in its contribution to our understanding of the coupling of the various components of the atmosphere-ionosphere-magnetosphere-satellites system. The rate of radial transport, which must supply the nearly 30 Terawatt energy consumption of the auroral zone, depends on the ionospheric conductivity and the gradients of the inward and outward going plasmas.The conductivity depends in turn on the rate of precipitation. In general, the system is extremely non-linear and an understanding of each of the components and its interaction with the others is needed in order to derive a coherent picture of how the Jovian magnetosphere and its attendant plasma function. We have also looked at the possible role of the satellite Europa and found that it is not extremely significant in populating the magnetosphere with plasma.

The latter phase of my Jupiter work began with my involvement in the work of the EPD team on Galileo. The discovery that the satellite Ganymede has an intrinsic magnetic field of sufficient magnitude to create a mini-magnetosphere inside the magnetosphere of Jupiter opened up totally new vistas of research. I have investigated the morphology of the energetic electron population, flow patterns around Ganymede, the structure of the ionosphere and the excitation of the aurora of Ganymede. I have also not ignored Io and Europa and have looked at the results of Galileo flybys and the phenomena discovered.


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Next: Saturn Up: Planetary Magnetospheres Previous: Planetary Magnetospheres