HR: 0800h
AN: SH51A-1183    [Abstracts]
TI: Voyager Observations of Galactic and Anomalous Cosmic Rays in the Heliosheath and Over the Solar Maximum Period of Cycle 23
AU: * McDonald, F B
EM: fm27@umail.umd.edu
AF: University of Maryland, IPST, CSS Bldg 224, Rm 3245, College Park, MD 20742 United States
AU: Webber, W R
EM: bwebber@nmsu.edu
AF: New Mexico State University, P.O. Box 30001, Las Cruces, NM 88003 United States
AU: Stone, E C
EM: ecs@srl.caltech.edu
AF: California Institute of Technology, 1200 East California Blvd, Pasadena, CA 91125 United States
AU: Cummings, A C
EM: ace@srl.caltech.edu
AF: California Institute of Technology, 1200 East California Blvd, Pasadena, CA 91125 United States
AU: Heikkila, B C
EM: bryant@mail630.gsfc.nasa.gov
AF: Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771 United States
AU: Lal, N
EM: Nand.Lal.1@gsfc.nasa.gov
AF: Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771 United States
AB: Voyager 1 crossed the heliospheric termination shock (TS) and entered the region of the heliosheath on December 16, 2004 (94 AU) just after the onset of a significant recovery from near-solar maximum conditions following the passage of the large interplanetary disturbances produced by the intense October/November 2003 solar activity. The spatial and temporal behavior of the energetic particle populations observed by Voyager 1 at the TS and in the heliosheath as well as the modulation of galactic and anomalous cosmic rays in the distant heliosphere in cycle 23 were markedly different from what was expected. At the TS the intensity of ACR He > 25 Mev/n and 2 - 20 MeV electrons, as well as GCRs, were below the intensity levels observed after the 2002.54 onset of termination shock particle events that persisted over most of the ensuing 2.3 year period. In the 8.5 months after the TS crossing there is a significant increase in ACR and GCR intensities as Voyager 1 has penetrated deeper into the heliosheath. However, there were generally similar increases at Voyager 2 which is still in the region of the supersonic solar wind some 19 AU closer to the Sun than Voyager 1. These observations suggest that the changes in modulation conditions as defined by the GCRs are playing a significant role in the evolution of the higher energy ACRs as well as the 2 - 20 MeV electron components. The challenge will be to separate spatial and temporal changes.
DE: 2104 Cosmic rays
DE: 2114 Energetic particles (7514)
DE: 2124 Heliopause and solar wind termination
SC: SPA-Solar and Heliospheric Physics [SH]
MN: Fall Meeting 2005