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Comet Shoemaker-Levy 9 Dust Size and Velocity DistributionsPre-impact observations of Comet Shoemaker-Levy 9 (S-L9) obtained with the Hubble Space Telescope are examined, and a model of an active, dust-producing comet is fitted to images of fragments G, H, K, and L. The model assumes steady isotropic dust emission from each fragment's sunlit hemisphere. Best-fit results indicate that the dominant light-scatterers in these fragments' comae were relatively large dust grains of radii 10 micrometers < R < 3 mm. The fragments' dust size distributions were rather flat in comparison to other comets, dN(R) proportional to R(sup -2.3 +/- 0.1), and the dust ejection speeds were approximately 0.5-1.5 m/s. The S-L9 fragments themselves were not detected directly, and upper limits on their radii are 1.0-1.5 km assuming an albedo a = 0.04. However, these fragments' vigorous production of dust, which ranges from 6 to 22 kg/s, places a lower limit of approximately 100 m on their radii at the moment of tidal breakup. Any fragments smaller than this limit, yet experiencing similar mass loss rates, would have dissipated prior to impact. Such bodies would fail to leave an impact scar at Jupiter's atmosphere, as was realized by fragments F, J, P(sub 1), P(sub 2), T, and U.
Document ID
20020022832
Acquisition Source
Headquarters
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Hahn, Joseph M.
(Lunar and Planetary Inst. Houston, TX United States)
Rettig, Terrence W.
(Notre Dame Univ. IN United States)
Date Acquired
August 20, 2013
Publication Date
January 1, 2000
Publication Information
Publication: Icarus
Publisher: Academic Press
Volume: 146
ISSN: 0019-1035
Subject Category
Astrophysics
Funding Number(s)
CONTRACT_GRANT: 5624.21-93A
CONTRACT_GRANT: NASW-4574
CONTRACT_GRANT: NAS5-26555
Distribution Limits
Public
Copyright
Other

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