Date of Award

8-2009

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Legacy Department

Physics

Advisor

King, Jeremy R

Committee Member

Brittain , Sean D

Committee Member

Hartmann , Dieter H

Committee Member

Lehmacher , Gerald A

Abstract

The concept of relic kinematic assemblages from dispersed stellar clusters has
remained contentious since Eggen's initial formulation of moving groups in the
1960's. However, the availability of high quality parallaxes from the Hipparcos
space astrometry mission has resulted in distance measurements for thousands of
nearby, seemingly isolated stars. With these newly determined distances, a
high resolution spectroscopic abundance analysis can be brought to bear on many of the
alleged members of these relic associations. If a structure is a relic of
an open cluster, the members can be expected to be monolithic in age and abundance
inasmuch as homogeneity is observed in young open clusters.

In this dissertation I have examined 34 members of
the Wolf 630 moving group using high resolution stellar spectroscopy. The stars
of the sample have been analyzed through a process known as chemical tagging
to determine abundance homogeneity and confirm the
existence of a homogeneous subsample of 20 stars. Fitting the homogeneous
subsample with Yale-Yonsei isochrones, yields a single evolutionary
sequence of ∼ 2.7 ± 0.5 Gyr.
Additionally basic N-Body simulations, using the NEMO Stellar Dynamics toolkit, have
been used to examine the kinematic evolution of typical star clusters in a model
galactic disk potential that has been studded with Giant Molecular clouds.
The results of these simulations suggests a high degree of kinematic coherence following
spatial dissolution, validating that open clusters can maintain a common kinematic
identity following their loss of spatial concordance.
It is, therefore, concluded that
moving groups can plausibly represent the relics of dissolved open clusters and that a 20 star
subsample of the Wolf 630 moving group sample of 34 stars could represent such a dispersed
cluster with an [Fe/H]=-0.01 ± 0.02
and an age of 2.7 ± 0.5 Gyr.

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