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Entry and fireball models vs. observations: What have we learned?

Published online by Cambridge University Press:  02 August 2016

Mordecai-Mark Mac Low*
Affiliation:
Astronomy & Astrophysics Center, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637, USA Also Department of Astronomy, University of Illinois at Urbana-Champaign

Abstract

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This review attempts to give a coherent explanation of the main observations of the entry Comet Shoemaker-Levy 9 and the aftermath of the resulting explosions by using models of the tidal breakup of the comet, the entry of individual fragments into the jovian atmosphere, and the resulting fireballs and plumes. A critical review shows that the models appear reasonably well understood. The biggest theoretical uncertainties currently concern how to best tie models of the entry to models of the resulting fireballs. The key unknown before the impact was the size and kinetic energy of the comet fragments. The evidence now available includes the behavior of the chain of fragments, the luminosity of the observed visible fireballs and later infrared emission, the chemistry of the spots, and the lack of seismic waves or perturbations at the water cloud pressure level. These observations point to the fragments having diameters under a kilometer, densities of order 0.5 gem“3, and kinetic energies of order 1027 erg.

Type
Research Article
Copyright
Copyright © Cambridge University Press 1996

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