Exploring the intriguing differences between Saturnian and Jovian magnetospheric neutral tori

Abstract:

The Jovian and Saturnian systems are similar in that they are relatively rapidly rotating gas giants with internal magnetic fields. They also possess ring systems and a large number of satellites (67 and 62, respectively) with a single moon in each system serving as the primary magnetospheric heavy particle source (Io and Enceladus, respectively) but with Jupiter’s primary particle source orbiting further from the planet. Jupiter’s magnetic field is over an order of magnitude stronger than the Saturnian field and is tilted by almost 10 degrees while Saturn’s magnetic field has no detectable tilt from its rotational axis. Additionally, Saturn is about twice as far from the Sun as Jupiter. Even considering these differences, however, it is very interesting that Jupiter’s magnetosphere is dominated by plasma while Saturn’s magnetosphere contains much more neutral than charged particles. Such a difference has extremely significant impacts on magnetospheric generation and dynamics. The wealth of information provided by Cassini over the last 10 years has provided unprecedented insight in to Saturn’s magnetosphere and has well positioned us to conduct studies comparing Saturn’s and Jupiter’s magnetospheres. A better understanding of neutral tori not only sheds valuable insight into past observations but also provides critical preparation for the upcoming ESA and NASA missions to the Jovian system.

For this work, we combine all available data for these two systems as well as neutral tori modeling to quantify the differences between these two magnetospheres. From the analysis, we illustrate how various neutral tori are generated and evolve. The results provide insight into the critical factors that determine how large gas giant magnetospheres can evolve into such significantly different configurations.