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Paper: Testing Be Disk Models with Optical Interferometry and Spectroastrometry
Volume: 464, Circumstellar Dynamics at High Resolution
Page: 85
Authors: Bjorkman, J. E.
Abstract: Be stars are hot, massive stars with gaseous circumstellar disks. A proposed model for creating these disks is viscous decretion, in which material is ejected from the star, placed into orbit, and spread outward by viscous diffusion. Here I review the use of observational disk diagnostics, including spectroscopic line formation, and how we use 3-D NLTE Monte Carlo simulations to predict the various observations. Next I focus on how we are employing high resolution imaging techniques like spectroastrometry and optical/near-IR interferometry to directly measure the disk kinematics and dynamics. The results of these tests provide strong support for the viscous decretion disk model. Finally I discuss how we are using time-dependent observations to test dynamical models of the disk. In particular, we now are able to determine that the disk viscosity parameter α 1, suggesting an instability produces the turbulent mixing in the disk. Furthermore, we have determined that the mass injection rate into the disk is much larger than the stellar wind mass loss rate, implying that the disk cannot be directly fed by the stellar wind.
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