Realistic numerical simulations of solar convection and oscillations in magnetic regions

We have used 3D, compressible, nonlinear radiative magnetohydrodynamics simulation to study the influence of magnetic fields of various strengths on convective cells and on the excitation mechanisms of acoustic oscillations by calculating the spectral properties of the convective motions and oscillations. The results reveal substantial changes of the granulation structure with increased magnetic field and a frequency-dependent reduction in the oscillation power in a good agreement with solar observations. These simulations suggest that the enhanced high-frequency acoustic emission at the boundaries of active regions (acoustic halo phenomenon) is caused by changes of the spatial-temporal spectrum of turbulent convection in a magnetic field, resulting in turbulent motions of smaller scales and higher frequencies than in quiet-Sun regions.