VOYAGER OBSERVATIONS OF THE MAGNETIC-FIELD, INTERSTELLAR PICKUP IONS AND SOLAR-WIND IN THE DISTANT HELIOSPHERE

Voyagers 1 and 2 are now observing the latitudinal structure of the he liospheric magnetic field in the distant heliosphere (the region betwe en similar or equal to 30 AU and the termination shock). Voyager 2 is observing the influence of the interstellar medium on the solar wind. The pressure of the interstellar pickup protons, measured by their con tribution to pressure balanced structures, is greater than or equal to the magnetic pressure and much greater than the thermal pressures of the solar wind protons and electrons in the distant heliosphere. The s olar wind speed is observed to decrease and the proton temperature inc rease with increasing distance from the sun. This mag result from the production of pickup ions by the charge exchange process with the inte rstellar neutrals. The introduction of the pickup ions into the dynami cs of the magnetised solar wind plasma appears to be an important new process which must be considered in future theoretical studies of the termination shock and boundary with the local interstellar medium.