Neutral Hydrogen Shell Structure Near Comet P/Halley Deduced from Vega-1 and Giotto Energetic Particle Data
- Alan Johnstone
Published Online: 26 MAR 2013
Copyright 1991 by the American Geophysical Union.
Cometary Plasma Processes
How to Cite
Verigin, M. I., McKenna-Lawlor, S., Richter, A. K., Szego, K. and Veselovsky, I. S. (1991) Neutral Hydrogen Shell Structure Near Comet P/Halley Deduced from Vega-1 and Giotto Energetic Particle Data, in Cometary Plasma Processes (ed A. Johnstone), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM061p0349
- Published Online: 26 MAR 2013
- Published Print: 1 JAN 1991
Print ISBN: 9780875900278
Online ISBN: 9781118663660
- Space plasmas;
An existing model based on Vega-l (Tunde-M) and Giotto (EPONA) energetic particle data, representing neutral gas shells expanding about comet Halley, has been up-dated by incorporating additional information concerning energetic particles recorded by Tunde-M, and neutral gas measurements recorded aboard the Vega-l and Vega-2 spacecraft, in the original data set. The modified model reproduces reasonably well the positions of the maxima in the intensity profiles of energetic cometary ions observed along the Vega and Giotto trajectories and it is estimated that the velocity of gas in the envisioned neutral shells is ∼7.3 km/s i.e. close to the velocity (∼8 km/s) of the slow hydrogen component of cometary neutrals. Detailed arguments are presented to support the suggestion that, at distances of 2–10×106 km from the comet nucleus, the energetic particles recorded in the quasi-periodic structures identified by the Tunde-M and EPONA instruments were protons.