Search Publications
Molecular Oxygen in Oort Cloud Comet 1P/Halley
Altwegg, K.; Rubin, M.; van Dishoeck, E. F. +1 more
Recently, the ROSINA mass spectrometer suite on board the European Space Agency's Rosetta spacecraft discovered an abundant amount of molecular oxygen, O2, in the coma of Jupiter family comet 67P/Churyumov-Gerasimenko of O2/H2O = 3.80 ± 0.85%. It could be shown that O2 is indeed a parent species and that…
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 …
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…
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 …
Sulfur-bearing Ions in the Ionosphere of Comet Halley
Reme, H.; Korth, A.; Lin, R. P. +3 more
This paper presents the radial density profiles of the ions corresponding to 35, 45, 47, and 47 amu, inside the ionopause of Comet Halley, obtained by the heavy ion analyzer PICCA on board the Giotto spacecraft. A photochemical model of the outflowing atmosphere/ionosphere, which emphasizes the sulfur chemistry in an H2O-dominated atmosphere, is u…
From Interstellar Dust to Comets: A Unification of Observational Constraints
Greenberg, J. Mayo; Hage, J. I.
The interstellar dust model of comets is numerically worked out to satisfy simultaneously several basic constraints provided by observations of Comet Halley, and to derive the porosity of coma dust. The observational constraints are (1) the strengths of the 3.4 and 9.7 micron emission bands, (2) the shape of the 9.7 micron band, (3) the amount of …
The Identification of H 3S + with the Ion of Mass per Charge (m/q) 35 Observed in the Coma of Comet Halley
Reme, H.; Korth, A.; Lin, R. P. +3 more
A sharp peak in the mass spectrum at 35 amu is observed by the heavy ion analyzer on board the Giotto spacecraft just inside the ionopause. This peak is identified with H3S(+) and it is argued that the dominant source of its likely parent molecule (H2S) is the observed distributed source of circumnuclear dust, rather than the central nucleus. In t…
Hydrogenated Amorphous Carbon Grains in Comet Halley?
Colangeli, L.; Fonti, S.; Bussoletti, E. +3 more
Recent IR observations of Comets Halley, Wilson, and Bradfield have shown the existence of an emission feature falling at around 3.4 microns. In this paper, it is shown that a good fit of both the IR continuum and the band can be obtained by assuming a simple thermal emission model based upon the optical properties of hydrogenated amorphous carbon…
Energetic Ion Fluxes in the Inner Coma of Comet P/Halley
Balsiger, H.; Young, D. T.; Goldstein, R. +3 more
The particle phenomenon observed inside the magnetic field-free cavity near the nucleus of Comet P/Halley by the Giotto Ion Mass Spectrometer High-Energy Range Spectrometer sensor is studied. The question of access to the cavity of particles ionized farther out in the coma is addressed. A quantitative model of a mechanism for creating the observed…
On the Possible Detection of Organic Dust-borne C 3H + Ions in the Coma of Comet Halley
Reme, H.; Korth, A.; Lin, R. P. +4 more
The heavy ion analyzer (PICCA) on board the Giotto spacecraft was used to determine the composition of positively charged ions in the environment of Comet Halley. Here it is argued that a distinct peak at 37 amu, observed in the mass spectrum inside the ionopause, is due to C3H(+). It is further argued that the dominant source of this ion, as well…