Is Vesta an intact and pristine protoplanet?
Abstract
It is difficult to find a Vesta model of iron core, pyroxene and olivine-rich mantle, and HED crust that can match the joint constraints of (a) Vesta's density and core size as reported by the Dawn spacecraft team; (b) the chemical trends of the HED meteorites, including the depletion of sodium, the FeO abundance, and the trace element enrichments; and (c) the absence of exposed mantle material on Vesta's surface, among Vestoid asteroids, or in our collection of basaltic meteorites. These conclusions are based entirely on mass-balance and density arguments, independent of any particular formation scenario for the HED meteorites themselves. We suggest that Vesta either formed from source material with non-chondritic composition or underwent after its formation a radical physical alteration, possibly caused by collisional processes, that affected its global composition and interior structure.
- Publication:
-
Icarus
- Pub Date:
- July 2015
- DOI:
- 10.1016/j.icarus.2015.03.029
- Bibcode:
- 2015Icar..254..190C
- Keywords:
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- Asteroid Vesta;
- Asteroids;
- composition;
- Planetary formation