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Large amplitude ion-acoustic solitons in a dusty plasma
Shukla, P. K.; Bharuthram, R.
Large amplitude ion-acoustic solitons in a plasma with a finite population of negatively charged dust grains are investigated. The effects of the dust grains on the soliton amplitude and Mach number are examined. It is found that both compressional and rarefactive solitons can occur.
Cometary dust trails I. Survey
Sykes, Mark V.; Walker, Russell G.
Cometary dust trails were first observed by the Infrared Astronomical Satellite and consist of large refractory particles ejected from short-period comets at low velocities. Consequently, they tend to be found near the orbital paths of their parent bodies, their long and narrow appearance reminescent of airplane contrails. An examination of the en…
0.7- to 23-µm photometric observations of P/Halley 1986 III and six recent bright comets
Gehrz, R. D.; Ney, E. P.
We report 0.7- to 23-µm observations of P/Halley 1986 III and six other recent bright comets. P/Halley was measured on 47 occasions between 1985 December 12 UT and 1986 May 6 UT, several times within hours of the perihelion passage on 1986 February 9 UT. Our data show that the strength of the 10-µm silicate emission feature and the tem…
Combined Infrared and Analytical Electron Microscope Studies of Interplanetary Dust Particles
Bradley, J. P.; Humecki, H. J.; Germani, M. S.
Ultramicrotomed thin sections (less than 100 nm thick) of eight chondritic interplanetary dust particles (IDPs) were studied by analytical electron microscopy and IR microspectroscopy with the objective of identifying IDPs or their specific components with IR spectral transmission characteristics at 10 microns similar to those of comets. Two IDPs …
Relationship between wave energy and free energy from pickup ions in the Comet Halley Environment
Johnstone, A. D.; Huddleston, D. E.
The free energy available from the implanted heavy ion population at comet Halley is calculated by assuming that the initial unstable velocity space ring distribution of the ions evolves toward a bispherical shell. Ultimately this free energy adds to the turbulence in the solar wind. We obtain upstream and downstream free energies separately for t…
The origin of complex organic ions in the coma of Comet Halley
Reme, H.; Korth, A.; Lin, R. P. +3 more
Heavy ion mass spectra were obtained in the inner coma of Comet Halley by the Giotto-PICCA instrument. Outside the cometary ionopause, where ≳2000 K ion temperatures limited the effective mass resolution to 3 amu, the spectra exhibit a series of distinct mass groups that are separated by a constant ≈ 15 amu and extend to at least 120 amu. We show …
Quasi-linear velocity space diffusion of heavy cometary pickup ions on bispherical diffusion characteristics
Coates, A. J.; Johnstone, A. D.; Huddleston, D. E.
We consider an ion transport equation describing the source, convection, adiabatic acceleration, and quasi-linear velocity diffusion of cometary pickup ions. The equation is solved numerically along solar wind plasma flow lines for the environment of comet Halley, to obtain distributions at positions on the Giotto spacecraft trajectory which may b…
Predictions of the solar wind interaction with Comet Grigg-Skjellerup
Coates, A. J.; Johnstone, A. D.; Huddleston, D. E.
The planned encounter of the Giotto spacecraft with comet Grigg-Skjellerup on 10th July 1992 promises to extend our knowledge of the solar wind interaction with comets substantially. While there have been spacecraft missions to comets before now, this mission is exploratory in the sense that the target comet is much older and therefore it has a mu…
Observations of Plasma Dynamics in the Coma of P/Halley by the Giotto Ion Mass Spectrometer
Schwenn, R.; Balsiger, H.; Ip, W. -H. +7 more
Observations in the coma of P/Halley by the Giotto ion mass spectrometer (IMS) are reported. The high-energy range spectrometer (HERS) of the IMS obtained measurements of protons and alpha particles from the far upstream region to the near ionopause region and of ions of mass 12-32 at distances of about 250,000 to 40,000 km from the nucleus. Plasm…
Properties of mass-loading shocks 2. Magnetohydrodynamics
Neubauer, F. M.; Zank, G. P.; Oughton, S. +1 more
The one-dimensional magnetohydrodynamics of shocked flows subjected to significant mass loading are considered. Recent observations at comets Giacobini-Zinner and Halley suggest that simple nonreacting MHD is an inappropriate description for active cometary bow shocks. The thickness of the observed cometary shock implies that mass loading represen…