In a paper published in the Royal Astronomical Society journal Monthly Notices, Zoltán Németh, a researcher at the ELKH Wigner Research Centre for Physics (Wigner RCP), sheds a completely new light on our understanding of the structure of the magnetosphere of giant planets.
When the strong magnetic field of giant planets interacts with solar wind, the stream of charged particles that are continuously released by the Sun, an enormous magnetized region is created that the solar wind is unable to penetrate. This structure is so large that if we could see Jupiter's magnetosphere, for example, it would be the most visible phenomenon in the Earth’s sky, dwarfing even the Sun itself.
Scientists previously believed that the magnetosphere of giant planets consisted of two significantly different parts. One is located close to the planet’s equator, where the field lines are closed, i.e. the field lines of a given latitude return to the surface of the planet in an arc in the vicinity of a similar latitude in the other hemisphere. These closed field lines orbit the planet. Close to the poles, on the other hand, we find open field lines, only one end of which connects to the planet, in the range of the polar caps. From here, the field lines turn towards the northern side, where together they form a long magnetotail.
A recently published article by Zoltán Németh suggests there may also be an area in the magnetosphere of giant planets where the field lines are closed as both ends are joined to the surface of the planet and do not rotate with it. Because the central points of these field lines are anchored in the magnetotail, they do not rotate around the planet. As the footholds attached to the planet’s surface rotate with the planet itself, the field lines in this region are twisted into huge eddies, known as vortices. Instead of rotating around the planet, the very rare, conductive material (plasma) found here also performs a vortical motion in the magnetotail.
Analysis of the measurement data from the Cassini space probe indicates that there is vortical movement created in Saturn’s magnetosphere, and that a proportion of Saturn’s magnetic field lines coalesce into magnetic vortices. The new model of Saturn’s magnetosphere sheds light on several properties that until now had been either impossible or difficult to explain.
Publication:
Zoltan Nemeth: Closed field line vortices in planetary magnetospheres. Monthly Notices of the Royal Astronomical Society, Volume 519, Issue 4, March 2023, Pages 5536–5542, Doi: 10.1093/mnras/stad030