The ion mass spectrometer aboard the Giotto spacecraft measured the composition and velocity distributions of cometary ions at distances of ∼7.5×l06 to ∼1,300 km from the nucleus of comet Halley. Well outside the bow shock, pick-up cometary H+ ions were found in a diffuse shell-like distribution. Heavier ions (C+, H2O+-group, CO+ and S+) with similar distributions have been identified at ≤3×l05 km. Solar-wind He2+ was found throughout the coma to as close as ∼5,000 km; He+ produced by charge exchange was seen inside ∼2×105 km. Deeper within the coma the main cometary hot-ion species identified were H+, H2+, C+, O+, OH+, H2O+, H3O+, CO+ and S+. A pile-up of heavy cometary ions was found at ∼104 km from the nucleus. Giotto crossed the contact surface at ∼4,600 km, based on changes in ion flow velocity and temperature. Inside, ion temperatures as low as ∼340 K and outflow velocities of ∼1 km s−1 were found. Outside the contact surface ion densities vary as r−2, with a transition to an r−l dependence approximately at the contact surface. A large C+ abundance throughout the coma indicates an unexpected direct source of atomic carbon. The nitrogen abundance, on the other hand, is relatively low.
This is a preview of subscription content
Subscribe to Journal
Get full journal access for 1 year
only $3.90 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Tax calculation will be finalised during checkout.
Get time limited or full article access on ReadCube.
All prices are NET prices.
Balsiger, H. et al. Eur. Space. Ag. spec. Publ. 1077, 129–148 (1986).
Gloeckler, G. et al. Geophys. Res. Lett. 13, 251–254 (1986).
Bierman, L., Brosowski, B. & Schmidt, H. U. Sol. Phys. 1, 254–284 (1967).
Ip, W.-H. & Axford, W. I. in Comets (ed. Wilkening, L. L.) 588–634 (University of Arizona Press, Tucson, 1982).
Schmidt, H. U. & Wegmann, R. in Comets (ed. Wilkening, L. L.) 538–560 (University of Arizona Press, Tuscon, 1982).
Johnstone, A. et al. Nature 321, 344–347 (1986).
Bame, S. J. et al. Science 232, 356–361 (1986).
Neubauer, F. et al. Nature 321, 352–355 (1986).
Shimizu, M. Astrophys. Space Sci. 40, 149–155 (1976).
Kunz, S. et al. Sol. Phys. 88, 359–376 (1983).
Feldman, P. D. in Comets (ed. Wilkening, L. L.) 461–479 (University of Arizona Press, Tucson, 1982).
A'Hearn, M. F., Feldman, P. D. & Schleicher, D. G. Astrophys. J. 274, L99–L103 (1983).
Aikin, A. C. Astrophys. J. 193, 263–264 (1974).
Ogilvie, K. W., Coplan, M. A., Bochsler, P. & Geiss, J. Science (in the press).
Ip, W.-H. Eur. Space Ag. spec. Publ. 169, 79–91 (1981).
Kissel, J. et al. Nature 321, 336–337 (1986).
Hanner, M. S. in Cometary Exploration Vol. 2 (ed. Gombosi, T. I.) 1–22 (Central Research Institute for Physics, Budapest, 1982).
About this article
Cite this article
Balsiger, H., Altwegg, K., Bühler, F. et al. Ion composition and dynamics at comet Halley. Nature 321, 330–334 (1986). https://doi.org/10.1038/321330a0
Space Science Reviews (2020)
Journal of Astrophysics and Astronomy (2020)
Imaging Plasma Density Structures in the Soft X-Rays Generated by Solar Wind Charge Exchange with Neutrals
Space Science Reviews (2018)
Brazilian Journal of Physics (2017)
Earth, Moon, and Planets (2015)