Search Publications

The photodissociation of water in cometary atmospheres

Crovisier, J.

It is now known from laboratory and theoretical works that following water photodissociation, the OH radical is created in excited states of rotation or vibration. This fact was neglected in previous models of water photodissociation in cometary atmospheres. The goal of the present paper is to update these models. The water life time is not change…

Evaluation of cometary dust parameters from numerical simulations: comparison with an analytical approach and the role of anisotropic emissions.

Fulle, M.

A numerical method is developed which models cometary dust tails by means of sample grains. The orbital motion of the grains is rigorously computed, avoiding any Finson-Probstein hypersonic condition and dust shell geometry approximation. The model is applied to the dust tails of Comet Seki-Lines 1962III and Comet Kohoutek 1973XII. The results sho…

The colour of Comet P/Halley's nucleus and dust

Keller, H. U.; Thomas, N.

Results are presented on the absolute calibration of the Halley Multicolor Camera (HMC), showing that HMC is 24 less sensitive than previously thought. The results are used to determine the reflectivity of the nuclear surface of the P/Halley comet, its color, and the color of the dust within 300 km of the nucleus. Results showed that the nucleus o…

Evidence for near-surface breezes on Comet P/Halley

Keller, H. U.; Thomas, N.

Halley Multicolor Camera (HMC) images taken of the nucleus of Comet P/Halley and its environment from on board ESA's spacecraft, Giotto, provide substantial evidence for flow of dust particles almost parallel to the surface at small cometocentric distances. This evidence is summarized and discussed with reference to other spacecraft experiments, g…