HR: 12:05h
AN: SH42A-08 INVITED     [Abstracts]
TI: A Theorist's View of Recent Observations by Voyager 1 in the Outer Heliosphere
AU: * Jokipii, J R
EM: jokipii@lpl.arizona.edu
AF: University of Arizona, Department of Planetary Sciences, Tucson, AZ 85721
AB: Recent observations of energetic particles on the Voyager 1 spacecraft in the outer heliosphere suggest new phenomena associated with its approach to the termination shock of the solar wind. Interpretations of the data have lead to controversy, with some claiming that the termination shock has been crossed and others not. I will review the published data from the relevant Voyager1 instruments and discuss their interpretation. No completely satisfactory model or theory which explains the basic data consistently has been produced. The various theoretical ideas advanced to explain the phenomena will be discussed. If the energetic particle data are taken to imply that the termination shock has indeed been crossed (Krimigis, et al, Nature, 2003) then we must understand why no compression of the magnetic field was observed (Burlaga, et al, GRL, 2003). However, if the termination shock has {\it not} been crossed (McDonald, et al, Nature, 2003), then the observed power-law energy spectrum down to very low energies reported by Krimigis, et al, is difficult to explain. Similarly, the radio data (Gurnett, et al, GRL, 2003) show no evidence of a shock crossing. These issues have been discussed, but there is, as yet, no generally accepted explanation of these data. The observed streaming anisotropies of the energetic particles provide valuable constraints on the physics, and they have been interpreted to support both the idea that the shock has been crossed and that it hasn't. Published theoretical analyses of particle acceleration and transport upstream of a shock (Jokipii and Giacalone, Ap. J. Lett 2004; Jokipii etal., Ap. J. Lett., 2004) suggest that the observed anisotropies are most-readily interpreted if Voyager 1 was near the termination shock, but that the shock was not crossed.
DE: 2104 Cosmic rays
DE: 2114 Energetic particles, heliospheric (7514)
DE: 2134 Interplanetary magnetic fields
DE: 2164 Solar wind plasma
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2004 AGU Fall Meeting