Origin of the solar wind: astrophysical and plasma-physical aspects of the problem

One of the unsolved questions in the astrophysical aspect of the problem of origin of the solar wind is when, during the evolution of the Sun as a star, the accumulation of its matter from the interstellar medium has been finished, and the dominant outflow of solar wind streams started. It is unknown in detail when and how it happened, though the commencement of thermonuclear reactions in the Sun's interior was of considerable importance in energetics and dynamics of the star; and this could result in such a change of the regimes. In this connection it is hypothesized that the accretion or plasma outflow from the star was dictated by the preceding evolution; i.e., by «memory» rather than by distribution of instantaneous densities, temperature, magnetic field, and other macroscopic parameters of the system that consists of this star, its nearest star environment, and interstellar gas. Depending on this, neighboring stars can be interstellar donors or accepters. Some of them can simultaneously or alternately fulfill both roles. The polytropic solution for centrally symmetrical flows derived by Bondi is degenerated in terms of a sign of radial velocity. It is capable of describing quasistationary regimes of both types. However, the transient process theory is still undeveloped. Thus the question as to whether there are stars that resemble the present-day Sun in their internal structure and parameters, but without stellar-wind emission or even with interstellar-gas accretion, may be only answered through observations. It is possible that such stars exist. This does not contradict to any laws of nature. Plasma-physical aspect of the problem of origin of the solar wind covers much shorter time intervals than the main evolution billion-year scale does. Therefore this aspect is better understood, though it is also rather complicated and still unsolved in many details, because of a multi-scale character of processes of flow formation. The solar wind as a permanent supermagnetosonic plasma outflow in the radial direction appears on the background of much more powerful irregular and unsteady motions, which are only partially ordered in the upper atmosphere and Sun's corona (turbosphere). The instantaneous solar-wind state is controlled by fluxes of free energy, matter, and impulse that enter the corona from the convective zone and solar atmosphere underlayers. Although the main physical mechanisms of transfer of free energy of the electromagnetic field and plasma are well-known, they need a quantitative investigation as applied to specific realizations in frequent and rare particle collisions in the Sun corona to determine non-local processes of formation of fields and plasma flows including the solar wind as well.