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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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.
|Title:||The long-term evolution and initial size of comets 46P/Wirtanen and 67P/Churyumov-Gerasimenko|
|Journal or Publication Title:||Monthly Notices Royal Astronomical Society|
|In ISI Web of Science:||Yes|
|Page Range:||pp. 1399-1406|
|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)|
|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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