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Beata Dziak-Jankowska 《Acta Geophysica》2010,58(2):392-416
This article is a continuation of the previous one considering the evolution of a long-period comet. The changes of the local
radius and the moment of inertia as well as the orientation of the rotation axis are calculated. With reference to the previous
model, the time-dependent orbital parameters are introduced. The procedure of sublimation-driven evolution is implemented
to the comets 67P/Churyumov-Gerasimenko, 9P/Tempel 1, and 81P/Wild. The inclination of the rotation axis of Comet Ch-G is
calculated. The position of the rotation axis is a result of the best fit of the water production rate curve received from
modelling to the observational water production rate curve. The method is verified through application to Comets 9P/Tempel
1 and 81P/Wild with well-known positions of the rotation axes. The best fit is for inclination of the rotation axis which
is close to the position of the rotation axis with minimum energy (maximum of the moment of inertia). For the best fitted
position of the rotation axis I = 90° and Φ = 60°, the largest decrease of radius was about 5.6 m in the northern polar region. The smallest decrease of radius, of about
0.3 m, was noticed on cometographic latitudes between 39° and 46°. 相似文献
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Beata Dziak-Jankowska Jacek Leliwa-Kopystyński Konrad J. Kossacki 《Acta Geophysica》2009,57(2):509-535
In this paper we intend to analyze how the sublimation of ice from cometary nuclei affects changes of the moments of inertia.
Our aim is to show general trends for different orientations of cometary nucleus’ rotation axis. Thus we apply numerical model
of a hypothetical homogeneous and initially spherical nucleus composed of water ice and dust. As an example we present simulations
for a model comet of the orbital elements and the nucleus size the same as determined for C/1995 O1 Hale-Bopp, a widely analyzed
long-period comet. We calculated water production from the nucleus and changes of the shape (initially spherical) and of the
moment of inertia versus time. Simulations are performed for the full range (0–90°) of inclinations I of the rotation axis. The second paramater related to the orientation of the rotation axis is the argument Φ (0–360°). The heat conductivity of the nucleus spans over the vast range, 0.04–4 W m−1 K−1. 相似文献
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Dziak-Jankowska Beata Leliwa-Kopystyński Jacek Królikowska Mał Gorzata 《Earth, Moon, and Planets》2002,90(1-4):35-44
The aim of this modelling work is to assess shape changes of cometary nuclei caused by sublimation of ices. The simplest possible
model is assumed with the nucleus being initially spherical and its thermal conductivity being neglected. We have calculated
the time-dependent sublimation flux versus cometographic latitude. If the rotation axis of the comet is inclined to the orbital
plane, then sublimation leads to non-symmetrical changes of the nucleus shape. Calculations were performed for the nuclei
of comets Hale–Bopp and Wirtanen. 相似文献
4.
Anna Swiatek Iwona Stanislawska Zbigniew Zbyszynski Beata Dziak-Jankowska 《Acta Geophysica》2014,62(1):259-269
Ionosphere coverage is likely to be a driver for the EGNOS coverage area. Hence, a study considering a dedicated ionosphere algorithm to improve the ionosphere coverage area has been conducted. The logic of the study is the following: the accuracy of the GPS signal depends mainly on the total electron content (TEC). At two close points, TEC changes in time in a very similar way; these are region dependent variables. This correlation decreases with growing distance between the observation points and is anisotropic. Based on TEC variogram analysis, the specific algorithm has been developed. This specific algorithm is presented and discussed. 相似文献
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