Semiclassical approximation for low-degree stellar p modes - II. Classical ray tracing

Abstract

Using ray-tracing techniques, we consider nearly forward refraction in the stellar interior of acoustic waves modified by buoyancy and gravity. Our analysis is based on a local dispersion relation developed to second order in the high-frequency asymptotic approximation. The phase shifts δℓ = δ0(ω) + ℓ(ℓ + 1)Dδ(ω) of the partial waves of stellar p modes, which govern the eigenfrequency equation in its classical limit, are developed in terms of explicit integrals containing the radial profiles of seismic parameters in the stellar interior. The accuracy of the resulting description of low-degree stellar p modes is tested using an evolutionary sequence of solar models.