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Astron. Astrophys. 325, 828-838 (1997)

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Interstellar gas filtration to the inner heliosphere under the selfconsistent influence of a pick-up ion modulated termination shock

Th. , Kausch , H.J. and Fahr

Institut für Astrophysik und Extraterrestrische Forschung der Universität Bonn, Auf dem Hügel 71, D-53121 Bonn, Germany

Received 1 October 1996 / Accepted 18 March 1997


In this paper we for the first time respect in terms of filtration properties the fact that the solar wind termination shock is likely to be a non-classical shock modulated by pick-up ions and anomalous cosmic ray particles. This type of shock produces a non-classical plasma interface between the inner heliosphere and the interstellar plasma with unusual thermodynamic properties like a cold and dense postshock solar wind plasma. We start out from the hydrodynamic description of the termination shock in a three-fluid approximation including the consistent dynamic interaction of the normal solar wind ion plasma, the heliospheric pick-up ions and the shock-generated, anomalous cosmic ray gas. Pick-up ions convected to the shock hereby serve as an effective seed for anomalous cosmic ray particles and strongly influence both location and nature of the shock and the post-shock plasma properties. On the other hand pick-up ions originate from interstellar neutral atoms penetrating into the inner heliosphere after passage over this post-shock plasma interface. By running an iterative computational procedure we arrive at a selfconsistent scenario. We present the neutral gas (H,O,N) and pick-up ion densities of this scenario and discuss these results in view of existing pick-up ion observations. Especially interesting are enhanced O- and N- pick-up ion densities within solar distances of 5AU resulting from reduced losses of O- and N-atoms in the post-shock interface.

Key words: shock waves – sun: solar wind – solar system: interplanetary medium – ISM: abundances, atoms, cosmic rays

Send offprint requests to: Th. Kausch


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© European Southern Observatory (ESO) 1997

Online publication: April 28, 1998