1994A&A...289..411H

β Lyr is an enigmatic object. Despite several decades of concentrated observational and theoretical effort, our understanding of the system is still rather poor. We discuss two existing structural models of the system, the massive torus model of Wilson (1981), and the low mass accretion disk model of Hubeny & Plavec (1991). In particular, we answer recent criticism of the low mass disk model expressed by the proponents of the massive disk hypothesis. We show that although both theories have a large degree of internal consistency, there are several serious physical objections against the massive disk model. In particular, such a model requires unrealistically low viscosity (large Reynolds number). Moreover, such massive disk is likely to be dynamically unstable. Finally, we propose several observational and theoretical approaches that could lead to construction of a more physically realistic model of the β Lyr system.