Non-LTE abundance corrections of iron and carbon in A-type and related stars

The statistical equilibrium of iron and carbon is investigated for main sequence stars ranging from effective temperatures of 7 000 K to 12 000 K, gravities of log g = 3.5 to log g = 4.5 and metallicities of [M/H]= -0.5 to [M/H]= +1.0. The non-LTE abundance corrections for iron are always positive over the whole range of effective temperatures, gravities and metallicities, They show a pronounced maximum whose position and strength depend strongly on the basic atmospheric parameters. In the case of carbon non-LTE effects depend basically on equivalent width. Up to an effective temperature of 10 000 K the non-LTE abundance corrections are always negative. In hotter atmospheres (T-eff > 10 000 K) the carbon model atom developed by Sturenburg & Holweger (1990) has been tentatively extended by including additional C II levels and transitions. However, this turns out to have little effect on the statistical equilibrium and non-LTE abundance corrections for neutral carbon.