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Astron. Astrophys. 327, 392-403 (1997)

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The cosmic rays mediated nonpolytropic solar wind interacting with the interstellar neutral matter

M. Banaszkiewicz and J. Ziemkiewicz

Space Research Center, Bartycka 18a, Pl-00716 Warsaw, Poland

Received 14 January 1997 / Accepted 29 May 1997


The solar wind spherical flow is considered under the combined action of gas pressure, magnetic field pressure and pressures of cosmic rays; both galactic and anomalous component. The interaction of solar wind ions with LISM neutrals is taken into account self-consistently by introducing the appropriate source terms in the flow equations. The numerical solutions of a set of five differential equations describing the system, obtained for different model parameters, provide a spectrum of possible configurations of the outer heliosphere. The formation of the solar wind termination shock is described and the shock position and strength are studied. The nonpolytropic solar wind is considered; the difference between the calculated pressure and the one resulting from the polytropic law are discussed. While taking into account the effects connected with the production of superthermal population leads to an increase of the shock compression ratio, the interaction with the LISM neutrals results in weaker shocks. The galactic cosmic rays push the shock inward, the anomalous component cosmic rays move it outward. Several sets of input parameters such as the initial speed and density of the solar wind (fast or slow), the cosmic ray diffusion coefficients, the density of interstellar neutrals, and the efficiency of the cosmic ray production at the shock are considered. For a typical distance to the solar wind termination shock of 60-100 AU, the efficiency of the cosmic rays production must be in the range 0-15%, in order to obtain well-behaved solutions in the downwind region.

Key words: heliosphere – solar wind – termination shock – cosmic rays – pickup ions

Send offprint requests to: M. Banaszkiewicz


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© European Southern Observatory (ESO) 1997

Online publication: April 8, 1998