Model Calculations of Oxygen Ion Fluxes from the Dissociation of H2O, CO, and CO2 at Gigamete Distances from Comet Halley

  1. Alan Johnstone
  1. P. W. Daly

Published Online: 26 MAR 2013

DOI: 10.1029/GM061p0341

Cometary Plasma Processes

Cometary Plasma Processes

How to Cite

Daly, P. W. (1991) Model Calculations of Oxygen Ion Fluxes from the Dissociation of H2O, CO, and CO2 at Gigamete Distances from Comet Halley, in Cometary Plasma Processes (ed A. Johnstone), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM061p0341

Author Information

  1. Max-Planck-Institut für Aeronomie, W-3411 Katlenburg-Lindau, Germany

Publication History

  1. Published Online: 26 MAR 2013
  2. Published Print: 1 JAN 1991

ISBN Information

Print ISBN: 9780875900278

Online ISBN: 9781118663660

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Keywords:

  • Comets;
  • Space plasmas;
  • Astrophysics

Summary

In a previous work, a method was developed to calculate densities of neutral particles emitted from comet Halley taking into account the Kepler trajectories that they describe. In that work, densities of the products of the dissociation of H2O were found out to distances of 24 Gm from the nucleus. Additionally ion fluxes were determined by integrating along solar wind streamlines to the point of “observation”. In the present work, densities and fluxes of oxygen atoms and ions are found from H2O, CO, and CO2. It is discovered that the last two dominate over the first beyond about 3 Gm from the nucleus mainly because of their larger ionization scale lengths. This causes the O density to be more circularly symmetric than predicted by the earlier study. The effect of changing the path of integration has been looked at and it is found that the ion fluxes are very sensitive to such variations. The usual practice of integrating along solar wind streamlines in the presence of strong pitch angle scattering is shown to be incorrect: one must do the calculation for many pitch angles and average the results. In the absence of pitch angle scattering the proper integration path is determined from the local solar wind and magnetic field conditions.