CHEMICAL ABUNDANCES IN EARLY B-TYPE STARS .5. METAL ABUNDANCES AND LTE NLTE COMPARISON

Chemical abundances of neon, magnesium, aluminium, sulfur, and iron are derived for a sample of 21 unevolved B-stars in the local field and nearby associations. While aluminium, sulfur, and iron are underabundant in nearly all stars, near solar abundances are found for magnesium and neon. In agreement with earlier results for carbon, nitrogen, oxygen, and silicon (Kilian 1992), the present results show no correlation with surface gravities or evolutionary states, which indicates that the metal abundances reflect the original composition of the interstellar medium. The results are supplemented by a comparison of LTE and NLTE abundances for C, N, O, Si, Mg, and Al. In most cases the differences amount to +/-(0.1-0.2) dex, which slightly exceeds the estimated accuracy of the NLTE abundance determination. However, a clear temperature gradient is evident for most elements, which indicates systematic LTE abundance errors with a maximum amplitude of 0.4 dex between 21 000 K and 31 000 K.