Three-dimensional structure of the solar wind: Variation of density with the solar cycle |
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| Authors: | P K Manoharan |
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| Institution: | (1) Radio Astronomy Centre, Tata Institute of Fundamental Research, 643001 Udhagamandalam (Ooty), India |
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| Abstract: | Interplanetary Scintillation (IPS) measurements obtained from a large number of compact radio sources (nearly 150 sources) distributed over the heliocentric distance range 15–175 solar radii (R( ) and heliographic latitude  75° N-75° S have been used to study the global three-dimensional density distribution of the solar wind plasma. Contours of constant electron-density fluctuations ( N
e) in the heliospheric plasma obtained for both the solar minimum and maximum show a strong solar latitude dependence. During low solar activity, the equatorial density-fluctuation value decreases away from the equator towards higher latitudes and is reduced by 2.5 times at the poles; the level of turbulence is reduced by a factor of 7; the solar-wind mass flux density at the poles is 25% lower than the equatorial value. However, during high solar activity, the average distribution of density fluctuations becomes spherically symmetric. In the ecliptic, the variation of N
e with the heliocentric distance follows a power law of the formR
–2.2 and it does not show any change with solar activity. |
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