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Investigating dynamical evolution of the disk for the Be star omega CMa over a range of wavelength with a variety of observational techniques

Published onJun 01, 2020
Investigating dynamical evolution of the disk for the Be star omega CMa over a range of wavelength with a variety of observational techniques

Be stars are main-sequence, fast-rotating stars that show emission lines in their optical spectra.These emission lines originate from a Keplerian circumstellar disk surrounding the central star.The Viscous Decretion Disk (VDD) model, where viscosity governs the evolution of the disk,seems to match the observations to explain the physics of these disks. We use the results of thebest fit on the V -band photometric data of the Be star ω CMa (Figure 1), provided by the 1-Dtime-dependent hydrodynamics code SINGLEBE and the Monte Carlo radiative transfer codeHDUST, from our previous work, to find models that match the observed photometric,polarimetric, and spectroscopic data of this star.Since various wavelength and observational techniques probe different parts of the disk, theyprovide strong constraints for developing realistic models. We find that the VDD model explainsthe polarimetric (Figure 2) and photometric (Figures 3 and 4) data well, qualitatively. However,we see some quantitative discrepancies that are clues to understand these disks more fully.Although our model could fit the spectroscopic data qualitatively (Figure 5), we find that the diskin our model is too dense at large radii, therefore, we considered alternatives to resolve thisproblem. First, we considered the effect of truncating the disk by an unresolved binary companionthat could potentially reduce the density in the outer part of the disk. This did not fix the problem.Then, we experimented with a radially varying viscosity parameter, α, that increased with thedistance from the central star. This model matches better and suggests a radially-varying α in Bedisks (Figure 6). Figure 1Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

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