The Oort Cloud (OC) is a roughly spherical cloud of comets surrounding the
solar system, stretching from well beyond the orbit of Neptune, half way to the
nearest star. This body of comets is interesting because it contains a record of the
gravitational perturbations suffered by the solar system over its
lifetime. Here, we investigate the effects of a particular class of
perturbing objects - enormous complexes of molecular gas called giant
molecular clouds (GMCs).
Recent evidence has shown that the classical picture of Oort Cloud
formation is inadequate to describe certain properties of the OC. To
re-investigate the dynamical evolution of the Oort Cloud,
we simulate the Sun's emergence from its natal
molecular cloud, and its subsequent encounters with GMCs. While the
role of giant molecular clouds in OC formation has
been explored before, they have been implemented in a general
way, not explicitly taking into account the 3D structure of the
cloud. In this research, we draw on an extensive body of evidence which suggests
that GMCs are not uniform, diffuse objects, but are instead organized
into high density clumps, connected by a very diffuse inter-clump
medium. Recent research has shown that GMCs are likely to be fractal
in nature, and so we have modeled them as fractal distributions
with dimension 1.6. We then perform N-body simulations of the passage
of the Sun and its Oort Cloud through such a
molecular cloud.
We find that the fractal structure of the GMC is, in fact,
an important parameter in the magnitude of the cometary energy
change. The significant energy changes occur as a result of
interactions with the GMC substructure, not simply as a result of its
overall density distribution. We find that interactions with GMCs can
be quite destructive to the OC, but can also serve to move comets from
tightly bound orbits to less tightly bound orbits, thus partially
replacing those lost to stripping. Simulations of the Sun's relatively
slow exit
from its birth GMC paint a picture of a potentially very destructive
era, in which a large portion of the OC's evolution may have occured. / Thesis (Master, Physics, Engineering Physics and Astronomy) -- Queen's University, 2009-09-21 13:05:17.527
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:OKQ.1974/5189 |
| Date | 23 September 2009 |
| Creators | Babcock, CARLA |
| Contributors | Queen's University (Kingston, Ont.). Theses (Queen's University (Kingston, Ont.)) |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English, English |
| Detected Language | English |
| Type | Thesis |
| Format | 12801267 bytes, application/pdf |
| Rights | This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner. |
| Relation | Canadian theses |
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