The Circumstellar Discs of Be Stars

Abstract

Circumstellar discs of Be stars are thought to be formed from material ejected from a fast-spinning central star. This material possesses large amounts of angular momentum and settles in a quasi-Keplerian orbit around the star. This simple description outlines the basic issues that a successful disc theory must address: 1) What is the mechanism responsible for the mass ejection? 2) What is the final configuration of the material? 3) How the disc grows? With the very high angular resolution that can be achieved with modern interferometers operating in the optical and infrared we can now resolve the photosphere and immediate vicinity of nearby Be stars. Those observations are able to provide very stringent tests for our ideas about the physical processes operating in those objects. This paper discusses the basic hydrodynamics of viscous decretion discs around Be stars. The model predictions are quantitatively compared to observations, demonstrating that the viscous decretion scenario is currently the most viable theory to explain the discs around Be stars.

12 pages, 5 figures, to appear in the proceedings of the IAU symposium 272

References in corpus (5)

• The Thermal Structure of the Circumstellar Disk Surrounding the Classical Be Star gamma Cassiopeia
• Non-LTE Monte Carlo Radiative Transfer: II. Non-Isothermal Solutions for Viscous Keplerian Disks
• Disk Loss and Disk Renewal Phases in Classical Be Stars I: Analysis of Long-Term Spectropolarimetric Data
• Constraining the Physical Parameters of the Circumstellar Disk of chi Ophiuchi
• Be Star Disk Models in Consistent Vertical Hydrostatic Equilibrium

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• SN 2018bsz: a Type I superluminous supernova with aspherical circumstellar material
• Outbursts and stellar properties of the classical Be star HD 6226
• Short-term variability and mass loss in Be stars VI. Frequency groups in $\gamma$ Cas detected by TESS
• New activity in the large circumstellar disk of the Be-shell star 48 Lib
• High-spatial-resolution simulations of Be star disks in binary systems: I. Structure and kinematics of coplanar disks
• Fast nodal precession of the disc around Pleione requires a broken disc
• Long-term optical variability of the Be/X-ray binary GRO J2058+42
• Red Be stars in the Magellanic Clouds?
• Exploring membership and variability in NGC 7419: An open cluster rich in super giants and Be type stars
• Spectral and timing analysis of BeXRB eRASSU J050810.4-660653 recently discovered in the Large Magellanic Cloud (LMC)
• Disc breaking through forced eccentricity growth