Amplitudes of non-radial oscillations driven by turbulence

Abstract

Turbulent motions in stellar convection zones generate acoustic energy, part of which is supplied to normal modes of the star. Amplitudes of these modes result from a balance between the efficiencies of excitation and damping processes in the convection zones. For radial oscillations, in the solar case, a good agreement between observations and theoretical modelling is reached (see for instance Belkacem et al. 2006b). We also compute the energy supplied by unit time by turbulent convection to the acoustic modes of α Cen A (HD 128620), a star which is similar but not identical to the Sun. In addition, we have developed a formalism that provides the excitation rates of non-radial modes excited by turbulent convection. It then allows us to investigate both p and g modes in the upper convection zones as well as in stellar convective cores. As a first application, we have estimated-and report here- the impact of non-radial effects on excitation rates and amplitudes of high-angular-degree solar p modes.