Search Publications
Optical properties of dust from Jupiter family comets
Levasseur-Regourd, A. C.; Hadamcik, E.
To try to define specific physical properties of the dust of Jupiter-family comets (JFCs), we compare the light scattered by them. Amongst the more than 1000 JFCs, less than 200 are numbered, 40 of them being rather bright. In the present work we use data from the latter. In situ observations of three nuclei show low albedo surfaces. The albedo of…
Probing the internal structure of the nuclei of comets
Lasue, J.; Levasseur-Regourd, A. C.; Hadamcik, E. +1 more
There is no direct evidence about the internal structure of cometary nuclei, which are mostly hidden by their gas and dust comae, and have not yet been orbited by any spacecraft. Their densities are low, typically of about 400 kg m -3 for 9P/Tempel 1 (that was impacted by the Deep Impact probe) and 67P/Churyumov-Gerasimenko (that is the…
Physical properties of cometary and interplanetary dust
Lasue, J.; Okada, Y.; Mukai, T. +1 more
In the absence of numerous in situ studies, physical properties of cosmic dust may be derived from observations of their light scattering and thermal properties, through numerical simulations making use of realistic assumptions. Estimations about cometary and interplanetary dust composition, structure, size, as well as about their light scattering…
Comparison of the dust distributions in the innermost comae of comets—1P/Halley and 19P/Borrelly spacecraft observations
Thomas, Nicolas; Tenishev, Valeriy; Combi, Michael +3 more
We present a comparative study of the inner comae of comets 1P/Halley and 19P/Borrelly using data from the Halley Multicolour Camera (HMC) onboard Giotto and the Miniature Integrated Camera and Spectrometer onboard Deep Space 1 (DS1). We show that the dust brightness dependence as a function of radial distance is different for both comets. We sugg…
Comet nuclei: Morphology and implied processes of surface modification
Keller, H. U.; Basilevsky, A. T.
Surface morphology and related issues for nuclei of three comets: Halley, Borrelly and Wild 2, are considered in the paper. Joint consideration of publications and results of our analysis of the comets' images led to conclusions, partly new, partly repeating conclusions published by other researchers. It was found that typical for all three nuclei…
An advanced physical model of cometary activity
Fulle, M.; Szegő, K.; Rodionov, A. V. +2 more
We describe the present state of an advanced physical model aimed at the simulation of the environment of active cometary nuclei. The model can handle the complicated shapes of real cometary nuclei, and is ready to handle alternative assumptions concerning the nucleus composition and structure; its present version is based on the simple, but hithe…
A flux enhancement measured in energetic particles(E ∼ 60-100 keV) by the epona instrument aboard Giotto close to P⧸Grigg-Skjellerup, and its interpretationas the signature of a companion comet
McKenna-Lawlor, Susan M. P.; Afonin, Valerie V.
A significant flux enhancement in energetic particles (E ∼ 60-⩾260 keV),showing internal fine structure interpreted to represent signatures produced during the traversalof various cometary boundaries in P⧸Grigg-Skjellerup, was recorded by the EPONA instrumentaboard spacecraft Giotto on 10 July 1992. A further internally structured flux enhancement…
Physical risks of landing on a cometary nucleus
Kührt, E.; Keller, H. U.; Knollenberg, J.
Comets originate from the outer solar system where the density and temperature of the planetary nebula were rather low. They form a distinct class of small solar system bodies and their physical properties differ considerably from those of any other known objects. The present knowledge of the cometary nucleus is cursory and driven more by imaginat…
Observation of interplanetary particles in a corotating interaction region and of energetic water group ions from comet Grigg-Skjellerup
Coates, A. J.; Neubauer, F. M.; Daly, P. W. +2 more
During the flyby of the Giotto S/C with comet Grigg-Skjellerup (G-S) (9-11 July 1992) energetic particles ( EH 2O > 60 keV, Ep > 30 keV, Eα > 3.5 MeV), magnetic fields and plasma ions were measured by three different detectors on board Giotto. The flyby period was characterized by high magnetic field …
Comparison of the wave energy transport at comets p/Halley and p/Giacobini-Zinner
Tsurutani, B. T.; Glassmeier, K. -H.; Neubauer, F. M. +2 more
Using magnetic field, plasma density and flow observations from spacecraft flybys of two comets, Elsässer variables are determined in order to study wave propagation directions. The inbound path of the Giotto spacecraft flyby of comet p/Halley is investigated outside the bow shock (between 10:36 and 19:11 UT on March 13, 1986, corresponding to dis…