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Title: The structure of a supernova-dominated cloudy interstellar medium
Author: Heathcote, Stephen Richard
ISNI:       0000 0001 3551 6806
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1983
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The interstellar medium in our Galaxy is highly: inhomogeneous and is kept in a highly disturbed state by the large input of1 energy by supernova explosions. Under such circumstances, supernova remnants and interstellar clouds co-exist in a symbiotic relationship the parameters of each being determined by those of the other through the agency of the various interactions between them. I here develop a simple model of such a supernova dominated cloudy interstellar medium (SDC-ISM). Although based on the work of McKee and Ostriker (l977) it has been extended in several important respects. This model is subjected to an exhaustive parameter search in order to locate the boundaries of its domain of validity and to establish the sensitivity of the model to its various input parameters. This representation of the SDC-ISM is then combined with a simple model of the structure of the galaxy constructed within the framework of the spiral density wave theory. It is shown that the high temperature component of the ISM is ubiquitous both within the spiral arms and in the interarm region. It then follows that the strong spiral shock assumed can only be supported if quite restrictive conditions are imposed on the galactic supernova rate and the interstellar gas density. During this investigation the need for a more detailed description of the dynamical interaction between an SNR shock and an interstellar cloud was identified. To meet this need I have constructed a highly approximate but simpl * model of this process which is then used to explore the behaviour of a cloud exposed to conditions prevalent in the SDC-ISM. I find that having been shocked a cloud is rarely allowed sufficient time to return to pressure equili brium with its surroundings before encountering a second shock. The disruption of a cloud by its passage through a blast wave is found to be quite effective and the half life of clouds cannot greatly exceed the mean interval between shocks striking a given cloud.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Astrophysics