Spectral diagnostics of late-type stars: Non-LTE and <3D> approach

Abstract

We determine effective temperature, metallicity, and microturbulence for a number of well-studied late-type stars. We use the new NLTE atomic model of Fe, and discuss the results for the MARCS models, as well as for the spatial and temporal averages of full 3D hydrodynamical simulations of stellar convection. It is shown that, contrary to the mean 3D models, certain limitations shall be imposed on the line formation and spectrum synthesis calculations with classical hydrostatic 1D models to obtain physically-realistic results.