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Theory of shock magnetization of asteroids Gaspra and Ida

Chen, George Q. and Ahrens, Thomas J. and Hide, Raymond (1996) Theory of shock magnetization of asteroids Gaspra and Ida. In: Shock Compression of Condensed Matter, 1995. AIP Conference Proceedings. No.370. American Institute of Physics , Melville, NY, pp. 929-932. ISBN 1-56396-566-6.

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The observed magnetism of asteroids such as Gaspra and Ida (and other small bodies in the solar system including the Moon and meteorites) may have resulted from an impact-induced shock wave producing a thermodynamic state in which iron-nickel alloy, dispersed in a silicate matrix, is driven from the usual low-temperature, low-pressure, α, kaemacite, phase to the paramagnetic, ε (hcp), phase. The magnetization was acquired upon rarefaction and reentry into the ferromagnetic, α, structure. The degree of re-magnetization depends on the strength of the ambient field, which may have been associated with a solar-system-wide magnetic field. A transient field induced by the impact event itself may have resulted in a significant, or possibly, even a dominant contribution, as well. The scaling law for catastrophic asteroid impact disaggregation imposes a constraint on the degree to which small planetary bodies may be magnetized and yet survive fragmentation by the same event. Our modeling results show it is possible Ida was magnetized when a large impact fractured a 125±22 km -radius proto-asteroid to form the Koronis family. Similarly, we calculate that Gaspra could be a magnetized fragment of a 45±15 km -radius proto-asteroid.

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Additional Information:© 1996 American Institute of Physics. Published online 05 May 1996. Research supported by NASA Grant NAGW-1941. Contribution #5592, Division of Geological and Planetary Sciences, California Institute of Technology.
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Caltech Division of Geological and Planetary Sciences5592
Series Name:AIP Conference Proceedings
Issue or Number:370
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Official Citation:Theory of shock magnetization of asteroids Gaspra and Ida George Q. Chen, Thomas J. Ahrens and Raymond Hide AIP Conf. Proc. 370, 929 (1996);
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:50682
Deposited By: Ruth Sustaita
Deposited On:22 Oct 2014 21:46
Last Modified:10 Nov 2021 18:59

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