Expansion of solar corona in the Sun's gravitational field...

6. Conclusions

[25] Expansion of the solar corona and formation of the heliospheric current sheet have been studied in numerical experiment. To solve a complete system of three-dimensional MHD equations, the PERESVET code was used. The following have been shown:

[26] 1. At corona expansion, the solar magnetic field is extended by the plasma flow, and a current sheet is formed. The sheet is not neutral. It contains a normal component of the magnetic field.

[27] 2. The current generation in the current sheet is similar to the current generation in a short-circuited MHD generator.

[28] 3. Division of magnetic lines into closed and open is not reasonable.

[29] 4. At typical corona parameters and T_i=T_e, the inclusion of gravitation and electron and ion temperature gradients does not lead to disturbance of stability of the solar wind flow formed. If T_ie, for the stable stationary flow to occur, an additional impulse, for instance, due to absorption of MHD disturbances propagating from the photosphere, is needed.

[30] 5. Transition from the subsonic flow to the supersonic one occurs at a distance of about sim 3 R. No discontinuities in parameters at transition to the supersonic flow are observed.