Mirror mode structures in the Saturn and Earth magnetosheath
Abstract
The magnetosheath of Earth and other planets is typically a high-beta anisotropic environment. Both magnetosheath boundaries are sources of free energy: Upstream particle reflection at the bow shock and ion foreshock region drive local instabilities and magnetic field line draping and compression at the magnetopause cause local plasma turbulence in front of the magnetopause. Thus, the result is a turbulent magnetosheath with a significant power over a wide range of the low-frequency spectrum. In this study, we investigate the origin and shape of mirror structures, and their characteristics in different regions of the Saturn's magnetosheath, comparing them with the properties of mirror mode waves in the magnetosheath around the Earth. Both the origin and shape of mirror structures are discussed using the observations of the magnetic field and plasma from the Cassini spacecraft during the 2004-2007 years. We find that these structures show a typically large anticorrelation between plasma and magnetic field fluctuations together with a higher occurrence rate of magnetic holes closer to the magnetopause. To discuss a process of formation and evolution of mirror structures in the Saturn's magnetosheath, we model the age of mirror structures using an analytic flow model based on an approach similar to the Earth's magnetosheath.
- Publication:
-
43rd COSPAR Scientific Assembly. Held 28 January - 4 February
- Pub Date:
- January 2021
- Bibcode:
- 2021cosp...43E1133G