Letter to the Editor

Diamagnetic effects of heliospheric Pick-up ions and magnetic fluxes in the outer heliosphere

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

Corresponding author: H. J. Fahr, hfahr@astro.uni-bonn.de

Received: 29 March 2004
Accepted: 12 May 2004

Abstract

For a long time it has been suggested that at larger solar distances the interplanetary magnetic field may not be behaving as predicted by Parker`s Archimedian spiral field model. This phenomenon, partly identified as the “magnetic flux deficit” paradox, appears as deficits in the azimuthal magnetic field components connected with “underwound” magnetic fields, though the pick-up ion decelerated solar wind should rather lead to excesses. Up to now no satisfactory explanation for this phenomenon has been presented. In this paper we study for the first time the diamagnetic effect of pick-up ions which systematically load the solar wind with suprathermal ions at its expansion to larger distances and diamagnetize the plasma. We shall demonstrate that such ions mainly reduce the azimuthal magnetic field component by their diamagnetic action. As we can show the field deficits can easily theoretically be explained by this effect. Also some new light is now shed on the problem of the magnetic field jump to be expected at the termination shock.