Radial Propagation of Waves

Abstract

For normal spheroidal displacement fields, a local dispersion equation in the radial coordinate is derived in the Cowling approximation. The conditions are examined under which local propagation of waves in the radial direction is possible. The analysis is divided into two parts: a first part relative to internal gravity waves, which propagate in incompressible layers that are subject to gravity, and a second part relative to acoustic waves, which propagate in compressible layers that are not subject to gravity. In both cases, the layer is considered, first in absence, then in presence of a density stratification. Next, for the two types of waves, the more general case of the radial propagation in a compressible layer with a density stratification that is subject to gravity is considered. A global representation of the radial propagation of acoustic and internal gravity waves throughout a star is given by the propagation diagram.