Trapped gravitational wave modes in stars with R > 3M - art. no. 044022

The possibility of trapped modes of gravitational waves appearing in stars with R>3M is considered. It is shown that the restriction to R<3M in previo us studies of trapped modes, using uniform density models, is not essential . Scattering potentials are computed for another family of analytic stellar models showing the appearance of a deep potential well for one model with R>3M. However, the provided example, although having a more realistic equat ion of state in the sense that upsilon(sound)<infinity, is unstable. On the other hand, it is also shown that for some stable models belonging to the same family but having R<3M, the well is significantly deeper than that of the uniform density stars. Whether there are physically realistic equations of state which allow stable configurations with trapped modes therefore re mains an open problem. [S0556-2821(99)00204-0].