Sliding Contacts in Planetary Magnetospheres

Abstract

In the planetary magnetospheres there are specific places connected with velocity breakdown, reconnection, and dynamo processes. Here we pay attention to sliding layers. Sliding layers are formed in the ionosphere, on separatrix surfaces, at the magnetopauses and boundaries of stellar astrospheres, and at the Alfvén radius in the equatorial magnetosphere of rapidly rotating strongly magnetized giant planets. Although sliding contacts usually occur in thin local layers, their influence on the global structure of the surrounding space is very great. Therefore, they are associated with non-local processes that play a key role on a large scale. There can be an exchange between different forms of energy, a generation of strong field-aligned currents and emissions, and an amplification of magnetic fields. Depending on the conditions in the magnetosphere of the planet/exoplanet and in the flow of magnetized plasma passing it, different numbers of sliding layers with different configurations appear. Some are associated with regions of auroras and possible radio emissions. The search for planetary radio emissions is a current task in the detection of exoplanets.

Can a Dynamo Mechanism Act at the Magnetopauses of Magnetic Rapidly Rotating Exoplanets?

“…where µ 0 is the permeability of the vacuum, n i and m i are the density and mass of ions, respectively. V A in the Jovian tail lobes is very large ~31 × 10 3 km s −1 [16,17], because the ion density there is extremely low ~10 −5 cm −3 [18] (much less than in the plasma sheet), and there are fewer heavy ions than in the equatorial region, which is rich in iogenic heavy ions. For these parameters, the Alfven radius in the tail lobes can be estimated as 2.5 × 10 3 R J [19], which exceeds the distance to the magnetopause.…”