[meteorite-list] Probing the history of Solar System through the cratering records on Vesta and Ceres

From: Shawn Alan <photophlow_at_meteoritecentral.com>
Date: Thu, 16 Jun 2011 00:41:32 -0700 (PDT)
Message-ID: <121104.76247.qm_at_web35404.mail.mud.yahoo.com>

Hello Listers

With The Dawn mission nearing?Vesta in July, I found an?article that is?engaging in the evolution of Vesta and Ceres and how these two asteroids interacted with Jupiter and survived the early violent evolution in the Solar System. Please take a look down below and learn some stuff about?Vesta and Ceres.
Probing the history of Solar System through the cratering
records on Vesta and Ceres
D. Turrini1?, G. Magni2, A. Coradini1
1Institute for Interplanetary Space Physics, INAF, Via Fosso del Cavaliere 100, 00133, Rome, Italy
2Institute for Space Astrophysics and Cosmic Physics, INAF, Via Fosso del Cavaliere 100, 00133, Rome, Italy
Dawn space mission will provide the first, detailed data of two of the major bodies
in the Main Asteroid Belt, Vesta and Ceres. Through its connection with HED mete-
orites, Vesta is known as one of the first bodies to have accreted and differentiated in
the Solar Nebula, predating the formation of Jupiter and surviving the violent evolu-
tion of the early Solar System. The formation time of Ceres instead is unknown, but it
should not postdate that of Jupiter by far, since the perturbations of the giant planet
stopped planetary accretion in the Main Asteroid Belt. In this work we modelled the
collisional histories of Vesta and Ceres at the time of the formation of Jupiter, assumed
to be the first giant planet to form. In this first investigation of the evolution of the
early Solar System, we did not include the presence of planetary embryos in the disk of
planetesimals but we concentrated on the role of the forming Jupiter and the effects
of its possible inward migration due to disk-planet interactions. Our results clearly
indicate that the formation of the giant planet caused an intense early bombardment
in the orbital region of the Main Asteroid Belt. We explored the effects of such bom-
bardment on Vesta and Ceres assuming different size distributions of the primordial
planetesimals. According to our results, Vesta and Ceres would not have survived the
Jovian early bombardment if the disk was populated mainly by large planetesimals
like those predicted to form in turbulent circumstellar disks. Disks dominated by small
bodies, like those predicted to form in quiescent circumstellar disks, or with a vary-
ing fraction of the mass in the form of larger (D > 100 km) planetesimals represent
more favourable environments for the survival of the two asteroids. The abundance
of planetesimals, especially the larger ones, proved a critical factor to this regards.
The extent of Jupiter?s radial migration due to disk-planet interactions proved itself
another critical factor. In those scenarios where they survive, both asteroids had their
surfaces saturated by craters as big as 150 km and a few as big as 200 ? 300 km.
In the case of Vesta, the Jovian early bombardment would have significantly eroded
(locally or globally) the crust and possibly caused effusive phenomena similar to the
lunar maria, whose crystallisation time would then be directly linked to the time of
the formation of Jupiter.


Shawn Alan
IMCA 1633
Received on Thu 16 Jun 2011 03:41:32 AM PDT

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