The formation and structure of fluffy cometary nuclei from random accumulation of grains

It 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 complet...

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Bibliographic Details
Published in:Astronomy and astrophysics (Berlin) 1990-08, Vol.235 (1-2), p.441-446
Main Author: Donn, B. D.
Format: Article
Language:English
Subjects:
Astronomy
Astrophysics
Comets
Earth, ocean, space
Exact sciences and technology
Interplanetary space
Solar system
Online Access:Get full text
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Summary:It 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.
ISSN:0004-6361
1432-0746