Planetary Current Sheets

Abstract:

Planetary magnetospheres are formed by the large-scale current systems. Here we consider magnetospheres of the magnetized planets (Mercury, Earth, Jupiter, and Saturn). Such planets create their intrinsic magnetic field, which is the inner magnetospheric magnetic source. The main permanently existing current systems for Mercury and Earth are the magnetopause currents and the tail currents. Terrestrial magnetosphere possesses also a ring current and field-aligned currents. The giant planets (Jupiter, and Saturn) have very strong own magnetic field, magnetopause and tail currents, field-aligned currents, and additionally a magnetodisc, which in a case of Saturn is called a ring current. Magnetodiscs are formed due to a rapid planetary rotation, large magnetic field, and a presence of the inter-magnetospheric plasma sources. For Jupiter, plasma originates by the Jovian moon Io, for Saturn, by its moon Enceladus. Magnetodics are examples of astrophysical discs in a strong magnetic field. We have shown that in the presence of a strong magnetic field the inner edges of astrophysical discs are located close to the Alfven radii from the central body regardless of the nature of their origin, material, and motion direction. This concerns to the Jovian and Kronian discs also. Magnetopause currents include current carried by the solar wind charged particles and another one created by the magnetospheric plasma. We have shown that magnetic field can be amplified in the thin transition layer just outside the magnetopause of a rapidly rotating planet (Jupiter). The same mechanism can act in the outer heliosheath just outside the heliopause.