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Enhancements of energetic particles near the heliospheric termination shock

McDonald, Frank B. and Stone, Edward C. and Cummings, Alan C. and Heikkila, Bryant C. and Lal, Nand and Webber, William R. (2003) Enhancements of energetic particles near the heliospheric termination shock. Nature, 426 (6962). pp. 48-51. ISSN 0028-0836. doi:10.1038/nature02066.

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The spacecraft Voyager 1 is at a distance greater than 85 au from the Sun, in the vicinity of the termination shock that marks the abrupt slowing of the supersonic solar wind and the beginning of the extended and unexplored distant heliosphere. This shock is expected to accelerate 'anomalous cosmic rays', as well as to re-accelerate Galactic cosmic rays and low-energy particles from the inner Solar System. Here we report a significant increase in the numbers of energetic ions and electrons that persisted for seven months beginning in mid-2002. This increase differs from any previously observed in that there was a simultaneous increase in Galactic cosmic ray ions and electrons, anomalous cosmic rays and low-energy ions. The low-intensity level and spectral energy distribution of the anomalous cosmic rays, however, indicates that Voyager 1 still has not reached the termination shock. Rather, the observed increase is an expected precursor event. We argue that the radial anisotropy of the cosmic rays is expected to be small in the foreshock region, as is observed.

Item Type:Article
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URLURL TypeDescription Information ReadCube access
Stone, Edward C.0000-0002-2010-5462
Cummings, Alan C.0000-0002-3840-7696
Additional Information:© 2003 Macmillan Publishers Limited. Received 28 May; accepted 14 September 2003. We thank J. D. Richardson and colleagues for making the Voyager 2 solar wind data available at <>. We also thank J. R. Jokipii, F. C. Jones, H. Moraal, V. Ptuskin and R. Caballero-Lopez for discussions on shock acceleration processes and particle flow in the vicinity of the acceleration region.
Group:Space Radiation Laboratory
Issue or Number:6962
Record Number:CaltechAUTHORS:20140826-084638532
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Official Citation:McDonald, F. B., Stone, E. C., Cummings, A. C., Heikkila, B., Lal, N., & Webber, W. R. (2003). Enhancements of energetic particles near the heliospheric termination shock. [10.1038/nature02066]. Nature, 426(6962), 48-51.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:48887
Deposited On:26 Aug 2014 19:25
Last Modified:10 Nov 2021 18:37

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