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Determination of comet Halley gas emission characteristics from mass loading of the solar wind
Coates, A. J.; Johnstone, A. D.; Huddleston, D. E.
We set out to fit the velocity profile of the solar wind during Giotto's approach to comet Halley with the mass loading produced by a simple model of the neutral particle distribution. The model assumes a constant gas production rate, Q, ionization rate, ν, and a radial expansion velocity, Ve, from the comet. It is used to calculate the…
Bulk properties and velocity distributions of water group ions at comet Halley: Giotto measurements.
Coates, A. J.; Glassmeier, K. -H.; Wilken, B. +3 more
In the region upstream of comet Halley, pickup heavy ions of cometary origin were directly observed by the Implanted Ion Spectrometer on Giotto. Here the authors discuss diffusion of this population in pitch angle and in energy, during the approach to the comet and on the outbound leg. The two data sets are compared and qualitative ideas on scatte…
Plasma parameters near the Comet Halley bow shock
Coates, A. J.; Wilken, B.; Kessel, R. L. +2 more
Plasma data from the Johnstone Plasma Analyzer on Giotto are used in a Rankine-Hugoniot analysis of Comet Halley bow shocks. The shock normals are obtained and compared with models and other estimates. Proton bulk parameters from the Fast Ion Sensor inbound are analyzed, and water group densities from the Implanted Ion Sensor (IIS) are obtained wh…
Comparison of picked-up protons and water group ions upstream of comet Halley's bow shock
Coates, A. J.; Neubauer, F. M.; Neugebauer, M.
Data are presented on the properties of picked-up cometary protons and water group (WG) ions observed upstream of the bow shock of comet Halley by the ion mass spectrometer and Johnstone plasma analyzer experiments on the Giotto spacecraft. The number of WG ions exceeded the number of cometary protons at cometocentric distances r<1.3×106
Erratum: Velocity space diffusion of pickup ions from the water group at comet Halley'' [J. Geophys. Res. 94, 9983 (1988)]
Coates, A. J.; Glassmeier, K. -H.; Wilken, B. +2 more