Electronic Thesis and Dissertation Repository

Degree

Doctor of Philosophy

Program

Astronomy

Supervisor(s)

Dr. Carol E. Jones

Abstract

This thesis is divided into 3 investigations. First we present a novel method to estimate the opening angles of Be star disks from interferometric axis ratio measurements, using Bayesian statistics and Monte Carlo techniques. A large set of theoretical axis ratios generated from disk models were compared to observational samples to determine which distribution best reproduces the observations. We find that the observed axis ratio distributions in the K-, H-, and N-band can best be explained by the presence of thin disks while measurements over the H$\alpha$ line point toward slightly thicker disks. Second, using a smoothed particle hydrodynamics (SPH) code, we studied the density structure of Be star disks in binary systems for a range of misalignment angles and disk viscosity. The truncation, warping, and density structure in the inner and outer parts of the disk are investigated. We find that these parameters affect both the truncation radius and the density of the outer disc, while the inner disk remains mostly unaffected. The scale height of our disks are also compared to analytical values. We find that the analytic values reproduces the scale height fairly well but underestimates the scale height in regions where density enhancements develop. Finally the shape and density structure of these enhancements were also investigated. We find that larger misalignment angles and viscosity values result in more tightly wound spiral arms with shallower density profiles. The orbital phase was shown to have very little effect on the structure of the spiral density enhancements.


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