Heliospheric current sheet
The sun has a magnetic field which can be removed only considered dipole field. Only in the polar regions are located at the time of sunspot minimum, the sharply defined coronal holes that can appear at any place at sunspot maxima. In the equatorial region are more active areas, which are characterized by closed magnetic field lines.
The charged particles existing in the solar wind (plasma) causes a moving away from the sun, a rotating magnetic field. In the filed of solar plasma space, the heliosphere, there is a point at which changes the polarity of the interplanetary magnetic field from north to south. Or in other words: There is a boundary layer which separates regions of the solar wind with oppositely directed magnetic fields. The result is a structure that rotates around the sun, and so far extends approximately at the level of the sun 's equatorial plane, such as the solar wind ranges. This field is named Heliospheric current sheet or in English Heliospheric current sheet, often abbreviated as HCS.
Form
The layer is about 10,000 km thick.
The shape depends strongly on the current magnetic field of the sun, which from the normal dipole to a field with eg can vary two north poles. In some publications it is in " ballerina skirt" ie ballerina tutu as a normal state. As the sun was training a second magnetic north pole in 2000, it was assumed a one billion kilometers large field of the shape of a snail shell. Indeed, measurements of the ESA - NASA Ulysses spacecraft were able to confirm this prediction.
Electric current flow
The electric current in the current layer is directed radially inward and has a magnitude of a maximum of 10-10 A / m ( 10-4 A / km ²).
In comparison, the Birkeland currents are 1000 times weaker astrophysical flows, which can be found in the Earth's environment.
History
The heliospheric current sheet was discovered by John M. Wilcox and Norman F. Ness. They released in 1965. During the 70 years KH shadows developed the first mathematical model for the shape of the current layer.