Centaur (planetoid)
Observations of Chiron in 1988 and 1989 near its perihelion found it to display a coma (a cloud gas and dust evaporating from its surface). It is thus now officially classified as both a comet and an asteroid, although it is far larger than a typical comet and there is some lingering controversy. Other centaurs are being monitored for comet-like activity: so far two, 60558 Echeclus, and 166P/NEAT 2001 T4 have shown such behavior. 166P/NEAT 2001 T4 was discovered while it exhibited a coma, and so is classified as a comet, though its orbit is that of a centaur. 60558 Echeclus was discovered without a coma but recently became active[10] , and so it is now accordingly also classified as both a comet and an asteroid.
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Theories of origin
The study of centaur development is rich in recent developments but still hampered by limited physical data. Different models have been put forward for possible origin of centaurs.
Simulations indicate that the orbit of some Kuiper Belt objects can be perturbed, resulting in the object's expulsion so that it becomes a centaur. Scattered disk objects would be dynamically the best candidates[11] for such expulsions, but their colours do not fit the bicoloured nature of the centaurs. Plutinos are a class of Kuiper Belt Object that display a similar bicoloured nature, and there are suggestions that not all plutinos' orbits are as stable as initially thought, due to perturbation by Pluto.[12] Further developments are expected with more physical data on KBOs.
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Notable centaurs
Well-known centaurs include:
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References
- ^ a b c Jewitt, David C.; A. Delsanti (2006). "The Solar System Beyond The Planets", Solar System Update : Topical and Timely Reviews in Solar System Sciences. Springer-Praxis Ed.. ISBN 3-540-26056-0. (Preprint version (pdf))
- ^ M. A. Barucci, A. Doressoundiram, and D. P. Cruikshank, "Physical Characteristics of TNOs and Centaurs" (2003), available on the web (accessed 3/20/2008)
- ^ Bauer, J. M., Fernández, Y. R., & Meech, K. J. 2003. "An Optical Survey of the Active Centaur C/NEAT (2001 T4)", Publication of the Astronomical Society of the Pacific", 115, 981 [1]
- ^ N. Peixinho1, A. Doressoundiram1, A. Delsanti, H. Boehnhardt, M. A. Barucci, and I. Belskaya Reopening the TNOs Color Controversy: Centaurs Bimodality and TNOs Unimodality Astronomy and Astrophysics, 410, L29-L32 (2003). Preprint on arXiv(pdf)
- ^ Hainaut & Delsanti (2002) Color of Minor Bodies in the Outer Solar System Astronomy & Astrophysics, 389, 641 datasource
- ^ A class of Magnesium Iron Silicates (Mg, Fe)2SiO4, common components of igneous rocks.
- ^ Dotto, E; Barucci, M A; De Bergh, C, Colours and composition of the centaurs, Earth, Moon, and Planets, 92, no. 1-4, pp. 157-167. (June 2003)
- ^ Jane X. Luu, David Jewitt and C. A. Trujillo Water Ice on 2060 Chiron and its Implications for Centaurs and Kuiper Belt Objects, The Astrophysical Journal, 531 (2000),L151-L154. Preprint on arXiv.
- ^ Y. R. Fernandez, D. C. Jewitt, S. S. Sheppard Thermal Properties of Centaurs Asbolus and Chiron, The Astronomical Journal, 123 (Feb. 2002),1050–1055. Preprint on arXiv.
- ^ Y-J. Choi, P.R. Weissman, and D. Polishook (60558) 2000 EC_98, IAU Circ., 8656 (Jan. 2006), 2.
- ^ for instance, the centaurs could be part of an "inner" scattered disc of objects perturbed inwards from the Kuiper belt [2].
- ^ Wan, X.-S; Huang, T.-Y. (2001). "The orbit evolution of 32 plutinos over 100 million year". Astronomy and Astrophysics 368: 700-705. doi:.
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See also
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External links
- List of Centaurs and Scattered-Disk Objects
- Centaurs from The Encyclopedia of Astrobiology Astronomy and Spaceflight
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