Cometary Pick-Up Ions Observed Near Giacobini-Zinner

  1. Thomas J. Birmingham and
  2. Alexander J. Dessler
  1. G. Gloeckler,
  2. D. Hovestadt,
  3. F.M. Ipavich,
  4. M. Scholer,
  5. B. Klecker and
  6. A.B. Galvin

Published Online: 19 MAR 2013

DOI: 10.1029/SP027p0028

Comet Encounters

Comet Encounters

How to Cite

Gloeckler, G., Hovestadt, D., Ipavich, F.M., Scholer, M., Klecker, B. and Galvin, A.B. (1988) Cometary Pick-Up Ions Observed Near Giacobini-Zinner, in Comet Encounters (eds T. J. Birmingham and A. J. Dessler), American Geophysical Union, Washington, D.C.. doi: 10.1029/SP027p0028

Author Information

  1. Department of Physics and Astronomy, University of Maryland, College Park, MD 20742

Publication History

  1. Published Online: 19 MAR 2013
  2. Published Print: 1 JAN 1988

ISBN Information

Print ISBN: 9780875902395

Online ISBN: 9781118668757



  • Cometary pick-up ions;
  • Energy density;
  • Number density;
  • Rest-frame distribution functions;
  • Ultra Low Energy Charge Analyzer (ULECA)


In-situ measurements of the rest-frame distribution functions of cometary pick-up water-group ions are used to derive the number and energy density of these ions as a function of distance from the Comet Giacobini-Zinner. The observed density profiles are found to be the same in the inbound and outbound passes and their shape is consistent with predictions of a simple model of pick-up ion production from neutrals of a given type which flow radially outward at ∼1 km/s and are lost at a rate A. Comparing predictions of this model with the measured density profiles we find that λ = 2 ˙ 10−6 sec−1 and that the production rate of water-group cometary molecules is 2.6 ˙ 1028/sec−1. The measured distribution functions of the pick-up water group ions may be represented by a two-segment power-law with a break at an energy EB ∼20 keV, corresponding to a speed, VB = 438(E/M)1/2;, of ∼500 km/s at distances greater than ∼105 km. The shapes of the distribution functions indicate that the interaction process of the solar wind with cometary ions is predominantly stochastic.