The Be star phenomena. II - Spectral formation and structure of envelopes

Abstract

The mechanisms of formation of the continuum and line spectra of Be stars and the morphology of their cool and hot envelopes are discussed in a review of recent theoretical and observational studies, supplementing the statistical evaluation of Kogure and Hirata (1982). Topics examined include the rapid rotation of Be stars, envelope dynamics, radiation fields, continuum emission, emission-line intensities, emission profiles, shell absorption lines, (general appearance, growth curves, central depths, and Balmer progression), cool-envelope structures (flattened vs vertically expanded, disk vs ring, axisymmetric vs elongated, and inhomogeneous vs multiple-component), circular-velocity laws, and the structure and origin of hot regions. Graphs, diagrams, and tables are provided.