HR: 13:40h
AN: SH43B-01 INVITED     [Abstracts]
TI: Voyager 1 Explores the Heliosheath
AU: * Stone, E C
EM: ecs@srl.caltech.edu
AF: Caltech, 220-47 Downs Laboratory, Pasadena, CA 91106 United States
AB: Since crossing the inward moving termination shock at 94 AU on December 16, 2004, Voyager 1 has revealed both expected and unexpected aspects of the heliosheath. The magnetic field was compressed by a factor of 3 across the shock, indicating a weak shock. However, for >5 solar rotations the magnetic polarity at Voyager 1 was unexpectedly positive, corresponding to the south polar magnetic field even though Voyager 1 is at 34 degrees north. This suggests that the radial speed of the heliosheath plasma convecting the magnetic filed must be comparable to that of Voyager 1 (17 km/s). A low speed is also evident in the small radial anisotropy of low energy ions and could result from a high inward shock speed or from a significant meridional deflection of the plasma flow. The shock is a steady source low energy (<3.5 MeV/nuc) termination shock particles (TSPs) with a spectrum consistent with diffusive acceleration at a weak shock. The TSP spectrum is also consistent with shock heating of interstellar pickup ions. In contradiction to expectations, the intensity of anomalous cosmic rays (ACRs) with >10 MeV/nuc did not peak at the shock, but continued to increase in the heliosheath, indicating that the ACR source is yet to be found. The intensities of galactic cosmic ray nuclei and electrons have also increased since crossing the shock as the effects of solar modulation continue to decrease. These and other recent results will be summarized.
DE: 2104 Cosmic rays
DE: 2114 Energetic particles (7514)
DE: 2124 Heliopause and solar wind termination
DE: 2134 Interplanetary magnetic fields
SC: SPA-Solar and Heliospheric Physics [SH]
MN: Fall Meeting 2005