# Cyclic Variability of the Circumstellar Disc of the Be Star $ζ$ Tau. II. Testing the 2D Global Disc Oscillation Model - Astrophysics > Solar and Stellar Astrophysics

Cyclic Variability of the Circumstellar Disc of the Be Star $ζ$ Tau. II. Testing the 2D Global Disc Oscillation Model - Astrophysics > Solar and Stellar Astrophysics - Download this document for free, or read online. Document in PDF available to download.

Abstract: Aims. In this paper we model, in a self-consistent way, polarimetric,photometric, spectrophotometric and interferometric observations of theclassical Be star $\zeta$ Tauri. Our primary goal is to conduct a criticalquantitative test of the global oscillation scenario. Methods. We have carriedout detailed three-dimensional, NLTE radiative transfer calculations using theradiative transfer code HDUST. For the input for the code we have used the mostup-to-date research on Be stars to include a physically realistic descriptionfor the central star and the circumstellar disc. We adopt a rotationallydeformed, gravity darkened central star, surrounded by a disc whose unperturbedstate is given by a steady-state viscous decretion disc model. We furtherassume that disc is in vertical hydrostatic equilibrium. Results. By adopting aviscous decretion disc model for $\zeta$ Tauri and a rigorous solution of theradiative transfer, we have obtained a very good fit of the time-averageproperties of the disc. This provides strong theoretical evidence that theviscous decretion disc model is the mechanism responsible for disc formation.With the global oscillation model we have successfully fitted spatiallyresolved VLTI-AMBER observations and the temporal V-R variations of theH$\alpha$ and Br$\gamma$ lines. This result convincingly demonstrates that theoscillation pattern in the disc is a one-armed spiral. Possible modelshortcomings, as well as suggestions for future improvements, are alsodiscussed.

Author: A. C. Carciofi, A. T. Okazaki, J-B. le Bouquin, S. Štefl, Th. Rivinius, D. Baade, J. E. Bjorkman, C. A. Hummel

Source: https://arxiv.org/