Olshevsky V. Scattering and transformation of magneto-acoustic waves in sunspots

Using 3D numerical modeling we studied the influence of the magnetic field and thermodynamic structure of a sunspot on the dynamics of MHD waves. Fast-to-fast and fast-to-slow mode transformation occurs in the photosphere of the spot model. Decrease of velocity amplitudes in the spot center is caused by the influence of the magnetic field. Acoustic halo appears mainly due to thermodynamic structure of the spot. We show that magnetic field has direct influence on wave travel times and must be accounted for in local helioseismology. We study NLTE formation of the Ba II 455.4 nm spectral line in 1D and 3D atmospheric models. Estimated Barium abundance is close to meteoritic one: A=2.16. Influence of atmospheric seeing on doppler diagnostic in this line is studied. We show that "bright points" on dopplergrams may appear in downstreams even in non-magnetized regions.