Contamination of the asteroid belt by primordial trans-Neptunian objects.

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Bibliographic Details
Title:	Contamination of the asteroid belt by primordial trans-Neptunian objects.
Authors:	Levison, Harold F., Bottke, William F., Gounelle, Matthieu, Morbidelli, Alessandro, Nesvorný, David, Tsiganis, Kleomenis
Source:	Nature. 7/16/2009, Vol. 460 Issue 7253, p364-366. 3p. 2 Graphs.
Subjects:	Asteroids, Solar system, Near-Earth objects, Sun, Neptunian theory, Igneous rocks, Meteorites, Achondrites, Meteors, Planets
Abstract:	The main asteroid belt, which inhabits a relatively narrow annulus ∼2.1–3.3 au from the Sun, contains a surprising diversity of objects ranging from primitive ice–rock mixtures to igneous rocks. The standard model used to explain this assumes that most asteroids formed in situ from a primordial disk that experienced radical chemical changes within this zone. Here we show that the violent dynamical evolution of the giant-planet orbits required by the so-called Nice model leads to the insertion of primitive trans-Neptunian objects into the outer belt. This result implies that the observed diversity of the asteroid belt is not a direct reflection of the intrinsic compositional variation of the proto-planetary disk. The dark captured bodies, composed of organic-rich materials, would have been more susceptible to collisional evolution than typical main-belt asteroids. Their weak nature makes them a prodigious source of micrometeorites—sufficient to explain why most are primitive in composition and are isotopically different from most macroscopic meteorites. [ABSTRACT FROM AUTHOR]
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Database:	Psychology and Behavioral Sciences Collection

Description
Abstract:	The main asteroid belt, which inhabits a relatively narrow annulus ∼2.1–3.3 au from the Sun, contains a surprising diversity of objects ranging from primitive ice–rock mixtures to igneous rocks. The standard model used to explain this assumes that most asteroids formed in situ from a primordial disk that experienced radical chemical changes within this zone. Here we show that the violent dynamical evolution of the giant-planet orbits required by the so-called Nice model leads to the insertion of primitive trans-Neptunian objects into the outer belt. This result implies that the observed diversity of the asteroid belt is not a direct reflection of the intrinsic compositional variation of the proto-planetary disk. The dark captured bodies, composed of organic-rich materials, would have been more susceptible to collisional evolution than typical main-belt asteroids. Their weak nature makes them a prodigious source of micrometeorites—sufficient to explain why most are primitive in composition and are isotopically different from most macroscopic meteorites. [ABSTRACT FROM AUTHOR]
ISSN:	00280836
DOI:	10.1038/nature08094