Sun and Solar Wind: Plasmas in the Heliosphere

Plasmas in interplanetary space originate from the Sun, as do most of the disturbances and waves embedded in them. The solar atmosphere, the corona, extends as solar wind far beyond the orbit of the outermost planet, Pluto, filling a cavity in the interstellar medium called the heliosphere. The solar magnetic field, frozen-in into the solar wind, is carried out and wound up to Archimedian spirals by the Sun’s rotation. Fluctuations and waves on different scales are superimposed, sometimes steepening to collisionless shock waves. The solar wind and the frozen-in magnetic field change during the solar cycle due to systematic changes in solar properties and transient disturbances related to solar activity. Detailed accounts on solar physics and the physics of the interplanetary medium are given in e.g. [113, 484, 572], and the solar corona and the physics of solar activity are described in e.g. [9,193, 244, 291, 410, 420, 424].