Locating Mass Loss:
Jennifer L. Hoffman |
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This dissertation presents a Monte Carlo radiative transfer
code optimized for the quantitative modeling of binary star
systems with circumstellar and other intrasystem material.
It models the observable flux and polarization variations
over the course of the binary cycle for a certain
geometrical matter configuration and viewing angle. With
this code, I have investigated the polarimetric signatures
of accretion disks in generalized binary systems and
described the variation of key polarimetric features with
disk geometrical and optical properties. Especially in cases
where some system parameters are known from light-curve
analysis, comparison of these model results with
polarimetric observations can help locate and describe gas
within the binary system, providing insights into the nature
of mass loss and nonconservative evolution in close
binaries. As a test case, I have used the code to create detailed models of the eclipsing interacting binary beta Lyr. By comparing the models with spectropolarimetric observations, I constrain the opening angle and albedo of the disk and find that its optical depth must vary with distance from the disk midplane. I also conclude that the polarization contributions from the mass-losing star and disk are not sufficient to reproduce the observed V-band polarized light curve of beta Lyr. This implies that the mass-gaining star, which does not contribute appreciably to the light curve of the system, must nevertheless be the source of a significant fraction of the total polarization of the system. This dissertation research has been supported in part by the Wisconsin Space Grant Consortium and Sigma Xi. |
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For more information, please send email to Jennifer. January 17, 2003 |