SIMBAD references

The results of three-dimensional hydrodynamic simulations of solar granulation, obtained using two different algorithms are presented. Sequences of 3-D hydrodynamic, time-dependent models have been used to determine iron abundance in the solar photosphere. The results of iron abundance determination from the equivalent widths and central depths of 42 FeI and 32 FeII lines are presented. The iron abundance has also been estimated from the line asymmetries and their absolute shifts. The conclusion was made that FeII lines are the most suitable for iron abundance determination in the LTE approximation, since they are not very sensitive to the temperature structure of models and to NLTE effects. To clear up the influence of the inhomogeneous structure of 3-D models on spectral line calculations, computations on the basis of 1-D models were carried out. The results of hydrodynamic simulations of granulation on Procyon, using the numerical technique developed for modelling solar granulation, are presented in comparison with the ones obtained for the Sun. The inhomogeneous models of the photosphere of Procyon permitted us to reproduce line asymmetries, observed in the spectrum of Procyon, and to estimate the rotation velocity of this star as 3.5 km/s. The temperature structure of the 3-D models of Sun and Procyon was also approximated by the mixing length theory with variable A (i.e. it was supposed that mixing length parameter A is varied with depth).