Search Publications
Remote infrared observations of parent volatiles in comets: A window on the early solar system
Dello Russo, N.; Mumma, M. J.; DiSanti, M. A. +3 more
Organic volatiles and water in Oort Cloud comets were investigated at infrared wavelengths. The detected species include H 2O, CO, CH 3OH, CH 4, C 2H 2, C 2H 6, OCS, HCN, NH 3, and H 2CO. Several daughter fragments (CN, OH, NH 2, etc.) are…
Comparative study of the dust emission of 19P/Borrelly (Deep space 1) and 1P/Halley
Soderblom, L. A.; Thomas, N.; Ho, T. M. +2 more
Images obtained by the Miniature Integrated Camera and Imaging Spectrometer (MICAS) experiment onboard the Deep Space 1 spacecraft which encountered comet 19P/Borrelly on September 22nd 2001 show a dust coma dominated by jets. In particular a major collimated dust jet on the sunward side of the nucleus was observed. Our approach to analyse these f…
The shape of a sublimating ice surface at the bottom of a non-volatile cylinder: Monte Carlo simulations and 2-D analysis
Keller, H. U.; Markiewicz, W. J.; Skorov, Yu. V.
Gas flow rate at a cometary surface depends on the microscopic structure of the porous dust-ice material that makes up the nucleus. The standard model for the structure of such material is a bundle of cylindrical, non-crossing tubes. Even within this idealized model the emergent flux depends on the shape of the sublimating ice surface at the botto…
Compressive character of low frequency waves driven by newborn ions at comet Grigg-Skjellerup
Coates, A. J.; Belmont, G.; Neubauer, F. M. +2 more
The investigation by Giotto of the environment of comet P/Grigg-Skjellerup has provided a large set of observations on cometary low-frequency waves for a weakly active comet, after the observations at comets P/Giacobini-Zinner and P/Halley. A large amount of waves are observed at frequencies close to the local water group ion cyclotron frequencies…
Comet halley's nucleus: A physical interpretation
Keller, H. U.; Thomas, N.
The nucleus of comet Halley was the first to be detected and observed by cameras on board spacecraft during the fly-bys in 1986. The interpretation of both these observations and of the results from other experiments as well as many subsequent corroborative measurements of comet Halley and of other comets are reviewed. Cometary nuclei are relative…
Diamagnetic effect of the ion pile-up region of comet halley
Neubauer, F. M.; Israelevich, P. L.; Ershkovich, A. I.
The ion pile-up region in the comet Halley ionosphere observed on the inbound leg of the Giotto trajectory is accompanied by a decrease of the magnetic field strength. This magnetic field dip is explained by means of a diamagnetic effect of the plasma density increase in the pile-up region. No similar magnetic effect of the enhanced plasma density…
Cometary ion pickup processes: Halley and Grigg-Skjellerup compared
Johnstone, A. D.
After Giotto's encounters with two comets of quite different gas production rates we attempt to compare the results to see:- a) to what extent theories which fitted the results at Halley could be applied to the much smaller Grigg-Skjellerup; b) whether the different relationship between the various scale lengths involved created any observable eff…
Comparison of the main magnetic and plasma features in the environments of comets Grigg-Skjellerup and Halley
Glassmeier, K. -H.; Neubauer, F. M.; Reme, H. +1 more
The successful flyby of Giotto at the weakly active comet P/Grigg-Skjellerup on July 10, 1992 has added a new set of observations to those obtained at the active comet P/Halley in March 1986 for the study of the solar wind - comet interaction. Despite the very different scales of the interaction regions for the two comets (10^6 km for Halley and 1…
Interplanetary magnetic field during the Giotto encounter and the induced magnetosphere of comet Halley
Neubauer, F. M.; Israelevich, P. L.; Ershkovich, A. I.
The direction of the interplanetary magnetic field (IMF) which governs the orientation of the Halley's magnetosphere was restored. Giotto magnetic and plasma data were represented in the coordinate system rotating with the IMF.
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 …