Please use this identifier to cite or link to this item:

The evolution of cometary activity

File Description Size Format  
uhm_phd_8729424_uh.pdf Version for UH users 2.66 MB Adobe PDF View/Open
uhm_phd_8729424_r.pdf Version for non-UH users. Copying/Printing is not permitted 2.69 MB Adobe PDF View/Open

Item Summary

Title:The evolution of cometary activity
Authors:Storrs, Alexander David
Date Issued:1987
Abstract:This dissertation is a two part investigation into the manner in which cometary activity originates. The first part is a simulation of the formation of a refractory residue layer on a surface subliming dirty ice. The second part traces to morphology of the sublimed ice (now gas) as it flows out through the inner coma. The formation of filamentary sublimate (FSR) residues from subliming dirty ice has been discussed by Saunders et al, (1984). The first part of this dissertation expands on the study of Saunders et al, by testing all major silicate mineral classes, and investigating the effects of organic materials on the formation of these residues. FSR is a light, strong material, an excellent thermal insulator, and its presence on the surface of cometary nuclei (and, potentially, on Martian polar layered terrain and icy satellites) would strongly affect the evolution of gas from the volatile ices it covers. FSR is formed when hydrated phyllosilicate grains are released from an icy matrix. These mineral grains attract a coating of several monolayers of semifluid water around themselves, even though the surrounding water is frozen. This semifluid layer allows the grains to coordinate and rebond into larger . units. These units are chemically identical to the original material, while retaining the physical morphology of the dirty ice. Organic tars can also bind mineral grains together. The structure formed is stronger and less porous than pure mineral FSR. Organic FSR resembles the structure observed to cover most of the nucleus of Halley's comet (Keller et al. 1986). The second part of this dissertation investigates the morphology of the outflow of the OH radical in the inner coma of Halley's comet. When a ratio is made of images of the comet in the OH (1-1) and (0-0) bands (around 3100 A), the resulting image maps the projection along the line of sight of the sunward velocity of the gas in the coma Qualitative interpretation of these images shows that, although constant velocity, spherically symmetric outflow is usually observed, gas jets and other asymmetries are not uncommon. Poor quantitative agreement with the theory (Schleicher and A'Hearn 1982) suggests either gas outflows on the order of 4 km/sec, or fine structure in the ratio which was not modeled by Schleicher and A'Hearn.
Thesis (Ph. D.)--University of Hawaii at Manoa, 1987.
Bibliography: leaves 81-85.
viii, 85 leaves, bound ill. 29 cm
Rights:All UHM dissertations and theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission from the copyright owner.
Appears in Collections: Ph.D. - Astronomy

Please email if you need this content in ADA-compliant format.

Items in ScholarSpace are protected by copyright, with all rights reserved, unless otherwise indicated.