The Excitation of Nonspherical Waves in Differentially Rotating Stellar Convective Envelopes

Abstract

A possible mechanism which excites nearly horizontal nonspherical waves in differentially rotating stellar convective envelopes is examined. It is shown that such waves can be excited either by the dy- namical instability due to the horizontal-velocity shear of differential rotations or by the overstable thermal instability in the convective envelope; the latter results from the cooperative interaction of the superadiabatic temperature stratification and thermal conduction. The excitation by the differential rotation is similar to that of Rossby waves in meteorology. A numerical example is considered for the Sun, and it is suggested that the sinusoidal deformation of quiescent prominences could be explained in terms of the excitation of such waves