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Negative ions in the coma of comet Halley
Chaizy, P.; Anderson, K. A.; Reme, H. +8 more
IN March 1986, the Giotto spacecraft encountered comet Halley, approaching to within ~600 km of the nucleus. Results from this encounter have shown that the inner coma contains a mixture of cometary neutral gas and dust, thermal ions and electrons, fast cometary pick-up ions, and decelerated solar-wind ions and electrons, as well as fast neutrals<…
Modeling of the thermal behavior and of the chemical differentiation of cometary nuclei
Schmitt, B.; Espinasse, S.; Klinger, J. +1 more
Taking into account the low values of average density reported for Comet P/Halley, a model of a porous comet nucleus has been developed. The model includes heat conduction through the solid matrix and heat and mass transfers due to the vapor phase circulating in the pore system. Sublimation and recondensation of volatile species within the nucleus…
Interpretation of the ion mass spectra in the mass per charge range 25-35 amu/e obtained in the inner coma of Halley's comet by the HIS-sensor of the Giotto IMS experiment
Altwegg, K.; Balsiger, H.; Geiss, J. +6 more
The IMS-HIS double-focusing mass spectrometer that flew on the Giotto spacecraft covered the mass per charge range from 12 to 56 (amu/e). By comparing flight data, calibration data and results of model calculations of the ion population in the inner coma, the absolute mass scale is established, and ions in the mass range 25 to 35 are identified. I…
The Organic Matter of Comet Halley as Inferred by Joint Gas Phase and Solid Phase Analyses
Korth, A.; Kissel, J.; Krueger, F. R.
During encounters with comet Halley, the experiment PICCA onboard GIOTTO measured the gas phase organic ion composition of the coma and the experiment PUMA onboard VEGA-1 measured the dust composition. Joining both results, we obtain a consistent picture of the parent organic matter from which dust and gas is produced. One recognizes a complex uns…
Observations of Solar Wind Ion Charge Exchange in the Comet Halley Coma
Balsiger, H.; Ip, W. -H.; Goldstein, B. E. +5 more
Giotto Ion Mass Spectrometer/High Energy Range Spectrometer (IMS/HERS) observations of solar wind ions show charge exchange effects and solar wind compositional changes in the coma of Comet Halley. As the comet was approached, the He(2+) to proton density ratio increased from 2.5 percent in the solar wind to about 4 percent about 1 hr before close…
Comparison of observed and calculated implanted ion distributions outside Comet Halley's bow shock
Coates, A. J.; Neugebauer, M.; Gombosi, T. I. +2 more
This paper compares calculated and measured energy spectra of implanted H+ and O+ ions on the assumption that the pickup geometry is quasi-parallel and about 1% of the waves generated by the cometary pickup process propagate backward (toward the comet). The model provides a good description of the implanted O+ and …
Ultra low frequency waves at the magnetic pile-up boundary of comet P/Halley
Glassmeier, K. -H.; Belmont, G.; Rème, H. +2 more
Around the magnetic pile-up boundary observed by Giotto at 135,000 km from the nucleus of comet Halley, plasma and magnetic features display evidence of ultra-low frequency modes. Outside the pile-up region, a large region is characterized by an anti-correlation between the electron plasma density and the magnetic field strength. The study of the …
Gas release from ice/dust mixtures
Krankowsky, D.; Mauersberger, K.; Hesselbarth, P. +4 more
Gas fluxes from insolated ice/dust mixtures were measured by pressure gauges and a mass spectrometer placed one meter in front of the sample. As soon as the insolation of about one solar constant was started a fast rise in H2O and CO2 emissions from the fresh surface was observed. Thereafter gas fluxes slowly decreased. When …
Densities and Abundances of Hot Cometary Ions in the Coma of P/Halley
Balsiger, H.; Ip, W. -H.; Goldstein, B. E. +3 more
The densities of the hot component in the ion population observed in the P/Halley coma by the ion mass spectrometer aboard the Giotto spacecraft has been recomputed, and the results are reported. Except for protons and H2(+), all densities are found to be at least an order of magnitude higher than predicted by the physicochemical model of Schmidt …
Comet P/Halley's dust production rate at Giotto encounter derived from Halley Multicolour Camera observations
Keller, H. U.; Thomas, N.
Optical constants for the dust from Comet P/Halley have been determined from Halley Multicolour Camera observations by applying the dust size distribution and the total mass impacting the Giotto spacecraft. The quantity of dust is found to be 0.080 rho exp 2/3 where rho is the dust particle bulk density in g/cu cm at an effective wavelength of 653…