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| Titel |
Modelling of the thermal evolution and differentiation of early Ceres |
| VerfasserIn |
Wladimir Neumann, Doris Breuer, Tilman Spohn |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250114252
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| Publikation (Nr.) |
 EGU/EGU2015-14565.pdf |
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| Zusammenfassung |
| The asteroid 1 Ceres is one of the remaining examples of the intermediate stages of planetary
accretion. Studies of such protoplanetary objects provide insight into the history of
the formation of Earth and other planets. One of Ceres’ remarkable properties is
the relatively low average bulk density of 2077±36 kg m-3[1]. Assuming a nearly
chondritic composition, this low value can be explained either by the presence of a
low density phase[2,3] (possibly water ice or hydrated silicates) that could have
differentiated forming an icy mantle over a rocky core[2,3], or by a relatively high average
porosity[4]. The shape and the moment of inertia of Ceres are consistent with both a
homogeneous and a differentiated structure. In the first case Ceres would be just a
large version of a common asteroid. In the second case this body could exhibit
properties characteristic for a planet rather than an asteroid: presence of a core, mantle
and crust, as well as a liquid ocean in the past and maybe still a thin basal ocean
today.
We study the evolution of a Ceres-like body via numerical modelling in order to draw
conclusions about the thermal metamorphism of the interior and its present-day structure. A
numerical model of an ice-silicate planetesimal, considering both water-rock and
metal-silicate differentiation of Ceres is being developed. In particular, accretion from a
km-sized porous seed to a Ceres-sized asteroid is considered. Further relevant processes, such
as transition from amorphous to crystalline ice, melting of ice, hydrothermal convection, as
well as melting and percolation of metal and silicates are included in the model. The model is
suited to prioritise between the two possible structures mentioned above and to constrain the
present-day state of Ceres’ interior. The necessary conditions for the differentiation as
well as the influence of the vital parameters, such as the accretion duration, will be
discussed.
[1] Thomas, C. et al. (2005) Nature, 437, 224–226. [2] McCord, T. B and Sotin, C. (2005)
JGR, 110, E05009. [3] Castillo-Rogez, J. C. and McCord, T. B. (2010) Icarus, 205, 443-459.
[4] Zolotov, M. Yu. (2009) Icarus, 204, 183-193. |
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