Abstract/Details

Gas trapping in amorphous water ice: A theoretical and experimental approach


2000 2000

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Abstract (summary)

The solar system began with the collapse of a dense molecular cloud, which is rich in atoms, dust grains and diverse molecules. The complexity of different physical and chemical processes which happened during the formation of the early solar system constitute a major topic within our scientific community, even though a complete model of the solar nebula including all such processes has not been constructed. This thesis deals with some of these chemical and physical processes and consists of two phases.

In the first phase of my work, I have studied the heating of water-ice grains during infall into the solar nebula from the surrounding collapsing cloud. The investigations in this phase extend previous studies (Lunine et al., 1991) in two aspects. Firstly, we revise the previous grain heating model. The calculations for large fluffy grains (up to 10μm) are conducted. Secondly, we explicitly incorporate terms associated with various exothermic and endothermic reactions which contribute to the thermal evolution of the grains in our computation. By tracking the threshold temperatures reached as a function of grain size, density and infall velocity, we are able to quantify the evolution of infalling interstellar grains.

Once the volatiles were brought in by the ice grains, codeposition of diversed volatiles on the surface of refractory grains happened in the cold solar nebula region. Disk dynamical evolution leads to a background temperature below 50K at distance beyond 20AU. Studies have shown that amorphous water ice forms at this temperature range. Amorphous ice can volumetrically absorbs a large amount of volatiles. My work in the second phase consists of investigations of amorphous water ice, especially its property of trapping various volatiles under conditions well outside the stability field of the condensed phases of the volatiles. A statistical thermodynamical model has been established. It is used to predict fractional abundances of trapped volatiles in different temperature and pressure conditions. Our investigations involve both theoretical and experimental studies.

Indexing (details)


Subject
Astronomy;
Astrophysics
Classification
0606: Astronomy
0606: Astrophysics
Identifier / keyword
Pure sciences; Gas trapping; Solar system; Water ice
Title
Gas trapping in amorphous water ice: A theoretical and experimental approach
Author
Dai, Wei
Number of pages
219
Publication year
2000
Degree date
2000
School code
0009
Source
DAI-B 61/05, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
ISBN
0599774029, 9780599774025
Advisor
Lunine, Jonathan I.
University/institution
The University of Arizona
University location
United States -- Arizona
Degree
Ph.D.
Source type
Dissertations & Theses
Language
English
Document type
Dissertation/Thesis
Dissertation/thesis number
9972126
ProQuest document ID
304579710
Copyright
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
http://search.proquest.com/docview/304579710/fulltextPDF
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