The Amplitude of Solar p-mode Oscillations from Three-dimensional Convection Simulations

The amplitude of solar p-mode oscillations is governed by stochastic excitation and mode damping, both of which take place in the surface convection zone. However, the time-dependent, turbulent nature of convection makes it difficult to self-consistently study excitation and damping processes through the use of traditional one-dimensional (1D) hydrostatic models. To this end, we carried out ab initio three-dimensional (3D), hydrodynamical numerical simulations of the solar atmosphere to investigate how p-modes are driven and dissipated in the Sun. The description of surface convection in the simulations is free from the tunable parameters typically adopted in traditional 1D models. Mode excitation and damping rates are computed based on analytical expressions whose ingredients are evaluated directly from the 3D model. With excitation and damping rates both available, we estimate the theoretical oscillation amplitude and frequency of maximum power, ν_max, for the Sun. We compare our numerical results with helioseismic observations, finding encouraging agreement between the two. The numerical method presented here provides a novel way to investigate the physical processes responsible for mode driving and damping, and should be valid for all solar-type oscillating stars.