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The formation and structure of fluffy cometary nuclei from random accumulation of grainsIt is now generally accepted that solid bodies in the solar system are formed by accumulation of solid grains. The mechanism of formation of smaller bodies, less than some tens of kilometers in radius, is investigated. These include planetesimals and comets. Results indicate that essentially complete agglomeration occurs for relative velocities of less than about 1000 cm/sec and fairly efficient mass build-up occurs up to 5000/cm. These velocities are consistent with current models of the primordial solar nebula. The temperature produced in a collision will be under 20 K. For ice/dust grains, the resultant aggregates will be of low density with their volatiles preserved. Cometary nuclei with radii of a few km will be irregularly shaped and fragile with low mean density and significant interanl density variations. The characteristics of such a structure could account for the observed properties of comets.
Document ID
19910025681
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Donn, B. D.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
August 14, 2013
Publication Date
August 1, 1990
Publication Information
Publication: Astronomy and Astrophysics
Volume: 235
Issue: 1-2,
ISSN: 0004-6361
Subject Category
Astrophysics
Accession Number
91A10304
Distribution Limits
Public
Copyright
Other

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