Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Negative ions in the coma of comet Halley


IN March 1986, the Giotto spacecraft encountered comet Halley, approaching to within 600 km of the nucleus. Results from this encounter have shown that the inner coma contains a mixture of cometary neutral gas and dust, thermal ions and electrons, fast cometary pick-up ions, and decelerated solar-wind ions and electrons, as well as fast neutrals1produced by charge exchange between pick-up ions and cold neutrals. Here we report the detection of a new component of the inner coma of comet Halley: negatively charged cometary ions. These ions are observed in three broad mass peaks at 7–19, 22–65 and 85–110 AMU, with densities reaching 1, 5x10-2 and 4x10-2cm-3, respectively, at a distance of 2,300 km from the nucleus. The ion species thought to be present include O-, OH-, C-, CH-, CN- and heavier complex CHO molecular ions. As negative ions are easily destroyed by solar radiation at 1 AU (ref. 2) an efficient production mechanism, so far unidentified, is required to account for the observed densities. The detection of negative ions in the coma near 1 AU implies that in similar neutral gas and dust environments farther away from the Sun (in Jupiter's or Saturn's magnetospheres3, for example), negative ions should also be present. If the negative-ion densities are large enough, they could play an important part in physical processes such as radiative transfer or charge exchange.

This is a preview of subscription content

Access options

Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.


  1. Eviatar, A. & Goldstein, R. Astrophys. J. 339, 545–557 (1989).

    ADS  CAS  Article  Google Scholar 

  2. Wekhof, A. Moon Planets 24, 157–173 (1981).

    ADS  CAS  Article  Google Scholar 

  3. Cheng, A. F. Astrophys. J. 242, 812–827 (1980).

    ADS  CAS  Article  Google Scholar 

  4. Rème, H. et al. J. phys. Engng 20, 721–731 (1987).

    ADS  Google Scholar 

  5. Rème, H. et al. Nature 321, 349–352 (1986).

    ADS  Article  Google Scholar 

  6. Rème, H. et al. Astr. Astrophys. 187, 33–38 (1987).

    ADS  Google Scholar 

  7. Coates, A. J. et al. Nature 327, 489–492 (1987).

    ADS  Article  Google Scholar 

  8. Anderson, K. A. et al. Astr. Astrophys. 187, 290–292 (1987).

    ADS  Google Scholar 

  9. d'Uston, C. et al. Ann. geophys. 7, 91–96 (1989).

    ADS  Google Scholar 

  10. Mazelle, C. et al. Geophys. Res. Lett. 16, 1035–1038 (1989).

    ADS  Article  Google Scholar 

  11. Neubauer, F. et al. Nature 321, 352–355 (1986).

    ADS  CAS  Article  Google Scholar 

  12. Balsiger, H. et al. Nature 321, 330–334 (1986).

    ADS  CAS  Article  Google Scholar 

  13. Wisemberg, J. & Kockarts, G. J. geophys. Res. 85, 4642–4652 (1980).

    ADS  CAS  Article  Google Scholar 

  14. Kettmann, G. et al. Ann. Geophys. 8, 229–238 (1990).

    ADS  Google Scholar 

  15. Mitchell, D. et al. Adv. space Res. 9, 35 (1989).

    ADS  CAS  Article  Google Scholar 

  16. Neubauer, F. et al. J. Phys. E20, 714–720 (1987).

    ADS  Google Scholar 

  17. Smith, G. P., Lee, L. C., Cosby, P. C., Peterson, J. R. & Moseley, J. T. J. chem. Phys. 68, 3818–3822 (1978).

    ADS  CAS  Article  Google Scholar 

  18. Lee, L. C. & Smith, G. P. J. chem. Phys. 70, 1727–1735 (1979).

    ADS  CAS  Article  Google Scholar 

  19. Krankowsky, D. et al. Nature 321, 326–329 (1986).

    ADS  CAS  Article  Google Scholar 

  20. Grün, E. & Reinhard, R. Spec. Publs Eur. Space Ag. 155, 7–21 (1981).

    Google Scholar 

  21. Arnaudeau, F. et al. Spec. Publs Eur. Space Ag. 224, 21–37 (1984).

    Google Scholar 

  22. Mendis, D. A. et al. Ann. geophys. 7, 99 (1989).

    ADS  Google Scholar 

  23. Mitchell, D. et al. Science 237, 626–628 (1987).

    ADS  CAS  Article  Google Scholar 

  24. Ip, W-H., Astrophys. J. 353, 290–296 (1990).

    ADS  Article  Google Scholar 

  25. Tawara, H. Atomic Data and Nuclear Data Tables 22, 491–525 (1978).

    ADS  CAS  Article  Google Scholar 

  26. Carlson, C. W., Curtis, D. W., Paschmann, G. & Michael, W. Adv. Space Res. 2, 67–70 (1982).

    Article  Google Scholar 

Download references

Author information

Authors and Affiliations


Rights and permissions

Reprints and Permissions

About this article

Cite this article

Chaizy, P., Rème, H., Sauvaud, J. et al. Negative ions in the coma of comet Halley. Nature 349, 393–396 (1991).

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI:

Further reading


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing