Line formation in solar granulation III. The photospheric Si and meteoritic Fe abundances

Using realistic hydrodynamical simulations of the solar surface convection as 3D, time-dependent, inhomogeneous model atmospheres, the solar photosphe ric Si abundance has been determined to be log epsilon(Si) = 7.51 +/- 0.04. This constitutes a difference of 0.04 dex compared with previous estimates based on the 1D Holweger-Muller (1974) model, of which half is attributabl e to the adopted model atmosphere and the remaining part to the improved qu antum mechanical broadening treatment. As a consequence, all meteoritic abu ndances should be adjusted downwards by the same amount. In particular the meteoritic Fe abundance will be log EF, = 7.46 +/- 0.01, in good agreement with the recently determined photospheric Fe abundance (Asplund et al. 2000 b). The existing uncertainties unfortunately prevent an observational confi rmation of the postulated effects of elemental migration of metals in the S un.