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Published September 1, 1995 | Published
Journal Article Open

Comet Shoemaker-Levy 9: Fragment and progenitor impact energy

Abstract

Initial observational data from the impact of fragments of Comet Shoemaker-Levy 9 (SL9) are compared with smoothed particle hydrodynamic (SPH) calculations to determine their pre-impact diameters and the equivalent diameter of the SL9 progenitor. Diameters (solid ice) of 2.0±0.1, 2.0±0.05, 2.1±0.04 and 1.9±0.05 km for fragments A, E, G1, and W are obtained from impact-induced plume heights from the Hubble Space Telescope (HST) data. Applying these values to scale apparent diameters for the balance of 18 SL fragments in Weaver et al.'s [1995] catalog of 22 objects yields a SL9 progenitor diameter of 5.0±1.8 km. This corresponds to total impact energy of 1.2 (+1.8−0.8) × 10^(30) erg. Such an energetic event occurs on Jupiter and Earth at least every 4,900 +4,700, −2,700, and ∼0.5 × 10^8 years, respectively.

Additional Information

© 1995 by the American Geophysical Union. Paper number 95GL02237. Received: February 16, 1995; revised: June 26, 1995; accepted: July 10, 1995. We thank Glenn Orton, James Friedson, Andrew Ingersoll, Reta Beebe, Heidi Hammel, Paul R. Weissman and the HST team for directing us to data and helpful discussion, and Eugene M. Shoemaker, Paul R. Weissman, Carolyn S. Shoemaker, George Field, and A. Ferrara for their preprints. We thank reviewer, M. Boslough, an anonymous reviewer, and W. Anderson for comments on the manuscript. Research supported by NASA. Contribution No. 5462, Division of Geological and Planetary Sciences, California Institute of Technology.

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August 20, 2023
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