Focusing on B-emission stars, we investigated a set of H$alpha$ equivalent widths calculated from observed spectra acquired over a period of about 4 years from 2003 to 2007. During this time, changes in equivalent width for our program stars were mon
itored. We have found a simple statistical method to quantify these changes in our observations. This statistical test, commonly called the F ratio, involves calculating the ratio of the external and internal error. We show that the application of this technique can be used to place bounds on the degree of variability of Be stars. This observational tool provides a quantitative way to find Be stars at particular stages of variability requiring relatively little observational data.
We present a numerical model describing a circularly symmetric gaseous disk around the Be star chi Ophiuchi. The model is constrained by long-baseline interferometric observations that are sensitive to the H-alpha Balmer line emission from the disk.
For the first time our interferometric observations spatially resolve the inner region of the circumstellar disk around chi Ophiuchi and we use these results to place a constraint on the physical extent of the H-alpha-emitting region. We demonstrate how this in turn results in very specific constraints on the parameters that describe the variation of the gas density as a function of radial distance from the central star.
We have computed theoretical models of circumstellar disks for the classical Be stars $kappa$ Dra, $beta$ Psc, and $upsilon$ Cyg. Models were constructed using a non-LTE radiative transfer code developed by citet{sig07} which incorporates a number of
improvements over previous treatments of the disk thermal structure, including a realistic chemical composition. Our models are constrained by direct comparison with long baseline optical interferometric observations of the H$alpha$ emitting regions and by contemporaneous H$alpha$ line profiles. Detailed comparisons of our predictions with H$alpha$ interferometry and spectroscopy place very tight constraints on the density distributions for these circumstellar disks.
