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Aerodynamic properties of fractal grains : Implications for the primordial solar nebula

Author
Donn, Bertram
Published
Sep 1, 1988.
Physical Description
1 electronic document
Additional Creators
Meakin, P.
Online Version

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Unclassified, Unlimited, Publicly available.
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Summary
Under conditions in the primordial solar nebula and dense interstellar clouds, small grains have low relative velocities. This is the condition for efficient sticking and formation of fractal aggregates. A calculation of the ratio of cross section, sigma, to number of primary particles, N, for fractal clusters yielded 1n sigma/N = 0.2635 + 0.5189N sup (-0.1748). This ratio decreases slowly with N and approaches a constant for large N. Under the usual assumption of collisions producing spherical compact, uniform density aggregates, sigma/N varies as N sup -1/3 and decreases rapidly. Fractal grains are therefore much more closely coupled to the gas than are compact aggregates. This has a significant effect on the aerodynamic behavior of aggregates and consequently on their evolution and that of the nebula.
Other Subject(s)
Collection
NASA Technical Reports Server (NTRS) Collection.
Note
Document ID: 19890003990.
Accession ID: 89N13361.
NASA, Washington, Infrared Observations of Comets Halley and Wilson and Properties of the Grains; p 166-171.
Terms of Use and Reproduction
No Copyright.
View MARC record | catkey: 15693024