Published online by Cambridge University Press: 23 September 2016
The proposed model is empirical; it is based on analysis of the available data on Be stars obtained in all the observable spectral regions, and it is required to be thermodynamically self-consistent. Rather than trying to answer the question: “What is the origin of the Be-phenomenon?” We ask: First. “What phenomena characterize empirically Be stars?” Second, “What thermodynamic characteristics are implied by the existence of such phenomena?” Third. “What inferences may be made an the atmospheric structure of a Be star from these empirical and thermodynamical characteristics?” The observed phenomena, their thermodynamical implications and the resulting model have each two aspects. On the one hand, the observational evidence for a nonradiatively heated, expanding chromosphere-corona implies the existence of both a nonradiative energy flux and a mass outflow from the photosphere. This first aspect is common to both Be and normal B stars, at least for the earliest subtypes.