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The long-term evolution and initial size of comets 46P/Wirtanen and 67P/Churyumov-Gerasimenko

Groussin, Olivier and Hahn, Gerhard and Lamy, Philippe and Gonczi, Robert and Valsecchi, Giovanni (2006) The long-term evolution and initial size of comets 46P/Wirtanen and 67P/Churyumov-Gerasimenko. Monthly Notices Royal Astronomical Society, 376, pp. 1399-1406. DOI: 10.1111/j.1356-2966.2007.11553.x.

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Abstract

We present a new method to study the long term evolution of cometary nuclei in order to retrieve their original size. We considered the two cases of comet 46P/Wirtanen and 67P/Churyumov-Gerasimenko. We calculated the past evolution of the orbital elements of both comets over 100,000 years using a Bulirsch- Stoer integrator and over 450,000 years using a Radau integrator, that we combined with a realistic model for the erosion of the nucleus to estimate their original size. We derived that for the long term evolution of the orbital elements of a comet, the main effect is the chaos resulting from close encounters with planets, and this effect is dominant whatever the choice of the integrator or the presence or not of non-gravitational forces. We estimated the dynamical lifetime of comet 46P to 133,000 years and 105,000 years for comet 67P. For the erosion, our model assumes a spherical nucleus made of a macroscopic mixture of pure dust and pure water ice, thermally decoupled. Erosion depends strongly on the active fraction and density of the nucleus. Assuming a density of 300 kg/m<sup>-3</sup> and an average active fraction over time of 10%, we obtain an initial radius of 1.3 km for 46P and 2.8 km for 67P. The upper limit is obtained assuming a density of 100 kg/m<sup>-3</sup> and an active fraction of 100%, and corresponds to an initial radius to 21 km for 46P and 25 km for 67P. Erosion due to water only occures under 4 AU and is restricted to short periods, !7% of the lifetime of a comet. We will apply this method to several other comets in the future.

Document Type:Article
Title:The long-term evolution and initial size of comets 46P/Wirtanen and 67P/Churyumov-Gerasimenko
Authors:
AuthorsInstitution or Email of Authors
Groussin, OlivierUniversity of Maryland,College Park
Hahn, GerhardUNSPECIFIED
Lamy, PhilippeLaboratoire d’Astronomie Spatiale du CNRS, Marseille
Gonczi, RobertObservatoire de la cote d’Azur, Nice
Valsecchi, GiovanniINAF-IASF, Roma
Date:September 2006
Journal or Publication Title:Monthly Notices Royal Astronomical Society
Refereed publication:Yes
In ISI Web of Science:Yes
Volume:376
DOI:10.1111/j.1356-2966.2007.11553.x
Page Range:pp. 1399-1406
Status:Published
Keywords:comets, 46P/Wirtanen, 67P/Churyumov-Gerasimenko
HGF - Research field:Aeronautics, Space and Transport (old)
HGF - Program:Space (old)
HGF - Program Themes:W EW - Erforschung des Weltraums
DLR - Research area:Space
DLR - Program:W EW - Erforschung des Weltraums
DLR - Research theme (Project):W - Vorhaben Asteroiden und Kometen (old)
Location: Berlin-Adlershof
Institutes and Institutions:Institute of Planetary Research > Asteroids and Comets
Deposited By: Dr.phil. Gerhard Hahn
Deposited On:18 Apr 2007
Last Modified:14 Jan 2010 23:39

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