Growth and sedimentation of dust grains in the primitive solar nebula.
Item
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Title
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Growth and sedimentation of dust grains in the primitive solar nebula.
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Identifier
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AAI8801681
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identifier
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8801681
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Creator
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Battaglia, Alessandro.
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Contributor
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Adviser: Vittorio M. Canuto
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Date
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1987
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Language
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English
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Publisher
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City University of New York.
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Subject
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Physics, Astronomy and Astrophysics
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Abstract
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The formation of the planets in the solar system is envisioned to occur via a gravitational instability in a thin layer of dust located at the midplane of the primitive solar nebula. The break-up of the dust layer gives rise to seed plants ('planetesimals') that, through successive collisions, eventually form the present-day planets.;This thesis addresses the problem of the formation of the dust layer, beginning with a configuration in which the dust particles are uniformly mixed with the nebula's turbulent gas. In the process, four basic ingredients are needed: (1) a model to describe the properties of turbulence in the nebula's gas, (2) a model for the structure of the primitive solar nebula, (3) a formalism to calculate the velocity of dust particles embedded in a turbulent fluid, and (4) a formalism to calculate the space-time evolution of the initial population of dust grains', e.g. mass distribution as a function of time and height above the nebula's midplane, etc.;To describe the properties of turbulence in the primitive solar nebula, we use the model by Canuto et al. (1987b) which has been favorably tested against a host of laboratory and astrophysical data.;The model of the primitive solar nebula by Cabot et al. (1987a, b), is also used, since it constitutes the most recent and physically plausible investigation of the problem.;The available results concerning the calculation of the velocity of particles embedded in a turbulent fluid were found to be unsatisfactory; therefore we developed a new formalism to express the latter quantity in terms of the properties of the turbulence in the fluid. A byproduct of this calculation is a new expression for the coefficient of turbulent diffusion, which should prove useful in future studies.;Following the space-time evolution of the grains, we developed a formalism that simulates the simultaneous processes of collisions and sedimentation of the dust grains in the primitive solar nebula.;The conclusion of this thesis is that for the model of the primitive solar nebula considered, the formation of a dust layer at midplane is very unlikely. The decay of turbulence seems a necessary condition for the onset of the gravitational instability that is thought to trigger the formation of the planets. (Abstract shortened with permission of author.).
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Phys.
