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Mediation of the solar wind termination shock by non-thermal ions

Abstract

Broad regions on both sides of the solar wind termination shock are populated by high intensities of non-thermal ions and electrons. The pre-shock particles in the solar wind have been measured by the spacecraft Voyager 1 (refs 1–5) and Voyager 2 (refs 3, 6). The post-shock particles in the heliosheath have also been measured by Voyager 1 (refs 3–5). It was not clear, however, what effect these particles might have on the physics of the shock transition until Voyager 2 crossed the shock on 31 August–1 September 2007 (refs 7–9). Unlike Voyager 1, Voyager 2 is making plasma measurements7. Data from the plasma7 and magnetic field8 instruments on Voyager 2 indicate that non-thermal ion distributions probably have key roles in mediating dynamical processes at the termination shock and in the heliosheath. Here we report that intensities of low-energy ions measured by Voyager 2 produce non-thermal partial ion pressures in the heliosheath that are comparable to (or exceed) both the thermal plasma pressures and the scalar magnetic field pressures. We conclude that these ions are the >0.028 MeV portion of the non-thermal ion distribution that determines the termination shock structure8 and the acceleration of which extracts a large fraction of bulk-flow kinetic energy from the incident solar wind7.

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Figure 1: Low-energy ions and electrons measured by Voyager 2 near the termination shock during 2007.
Figure 2: Energetic ions and electrons measured by Voyager 2 during 2005–2007.

References

  1. Krimigis, S. M. et al. Voyager 1 exited the solar wind at a distance of 85 au from the Sun. Nature 426, 45–48 (2003)

    ADS  CAS  Article  Google Scholar 

  2. McDonald, F. B. et al. Enhancements of energetic particles near the heliospheric termination shock. Nature 426, 48–51 (2003)

    ADS  CAS  Article  Google Scholar 

  3. Stone, E. C. et al. Voyager 1 explores the termination shock region and the heliosheath beyond. Science 309, 2012–2020 (2005)

    ADS  Google Scholar 

  4. Decker, R. B. et al. Voyager 1 in the foreshock, termination shock, and heliosheath. Science 309, 2020–2024 (2005)

    ADS  CAS  Article  Google Scholar 

  5. Krimigis, S. M. et al. in Connecting Sun and Heliosphere (Proc. Solar Wind 11/SOHO 16 Conf.) (eds Fleck, B., Zurbuchen, T. H. & Lacoste, H.) 21–28 (ESA, Noordwijk, 2005)

    Google Scholar 

  6. Decker, R. B. et al. in Physics of the Inner Heliosheath: Voyager Observations, Theory, and Future Prospects (Proc. 5th IGPP Internat. Astrophys. Conf.) (eds Heerikhuisen, J., Florinski, V., Zank, G. P. & Pogorelov, N. V.) 73–78 (AIP, Melville, New York, 2006)

    Google Scholar 

  7. Richardson, J. D. et al. Cool heliosheath plasma and deceleration of the upstream solar wind at the termination shock. Nature 10.1038/nature07024 (this issue)

  8. Burlaga, L. F. et al. Magnetic fields at the solar wind termination shock. Nature 10.1038/nature07029 (this issue)

  9. Gurnett, D. A. & Kurth, W. S. Intense plasma waves at and near the solar wind termination shock. Nature 10.1038/nature07023 (this issue)

  10. Krimigis, S. M. et al. The Low Energy Charged Particle (LECP) experiment on the Voyager spacecraft. Space Sci. Rev. 21, 329–354 (1977)

    ADS  Article  Google Scholar 

  11. Richardson, J. D. et al. Source and consequences of a large shock near 79 AU. Geophys. Res. Lett. 33, L23107 (2006)

    ADS  Article  Google Scholar 

  12. Opher, M., Stone, E. C. & Liewer, P. C. The effects of a local interstellar magnetic field on Voyager 1 and 2 observations. Astrophys. J. 640, L71–L74 (2006)

    ADS  Article  Google Scholar 

  13. Pogorelov, N. V. in Physics of the Inner Heliosheath: Voyager Observations, Theory, and Future Prospects (Proc. 5th IGPP Internat. Astrophys. Conf.) (eds Heerikhuisen, J., Florinski, V., Zank, G. P. & Pogorelov, N. V.) 3–13 (AIP, Melville, New York, 2006)

    Google Scholar 

  14. Pogorelov, N. V., Stone, E. C., Florinski, V. & Zank, G. P. Termination shock asymmetries as seen by the Voyager spacecraft: The role of the interstellar magnetic field and neutral hydrogen. Astrophys. J. 668, 611–624 (2007)

    ADS  CAS  Article  Google Scholar 

  15. Jokipii, J. R., Giacalone, J. & Decker, R. B. Energy spectra of energetic particles upstream of the termination shock. Eos 88 (Fall meeting), abstr. SH11A–07 (2007)

  16. Washimi, H. et al. A forecast of the heliospheric termination-shock position by three-dimensional MHD simulations. Astrophys. J. 670, L139–L142 (2007)

    ADS  Article  Google Scholar 

  17. le Roux, J. A., Webb, G. M., Florinski, V. & Zank, G. P. A focused transport approach to pickup ion shock acceleration: Implications for the termination shock. Astrophys. J. 662, 350–371 (2007)

    ADS  Article  Google Scholar 

  18. Giacalone, J. & Jokipii, J. R. Energetic particles around the termination shock: Numerical simulations for a blunt shock with cross-field diffusion. Astrophys. J. 649, L137–L140 (2006)

    ADS  CAS  Article  Google Scholar 

  19. Fisk, L. A., Gloeckler, G. & Zurbuchen, T. H. Acceleration of low-energy ions at the termination shock of the solar wind. Astrophys. J. 644, 631–637 (2006)

    ADS  Article  Google Scholar 

  20. Burlaga, L. F. et al. Crossing the termination shock into the heliosheath: magnetic fields. Science 309, 2027–2029 (2005)

    ADS  CAS  Article  Google Scholar 

  21. Gurnett, D. A. & Kurth, W. S. Electron plasma oscillations upstream of the solar wind termination shock. Science 309, 2025–2027 (2005)

    ADS  CAS  Article  Google Scholar 

  22. Richardson, J. D. et al. Relation between the solar wind dynamic pressure at Voyager 2 and the energetic particle events at Voyager 1. J. Geophys. Res. 110, A09106 (2005)

    ADS  Article  Google Scholar 

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Acknowledgements

Work at the Johns Hopkins University Applied Physics Laboratory was supported by the Voyager Interstellar Mission under NASA grant NNX07AB02G.

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Correspondence to R. B. Decker.

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Decker, R., Krimigis, S., Roelof, E. et al. Mediation of the solar wind termination shock by non-thermal ions. Nature 454, 67–70 (2008). https://doi.org/10.1038/nature07030

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