Non-LTE Abundance Analysis of Main-Sequence A–B Stars. III. Normal-Star Criteria

Abstract

We have determined the fundamental parameters (effective temperature \(T_{\textrm{eff}}\), surface gravity, and radius) and chemical composition for six stars of spectral types A–B: HD 186689 (\(\upsilon\) Aql), HD 58142 (21 Lyn), HD 145788, HD 192907 (\(\kappa\) Cep), HD 85504 (7 Sex), and HD 38899 (134 Tau), based on the analysis of high-resolution spectra and spectrophotometric observations. The chemical abundances were determined in the approximation of local thermodynamic equilibrium (LTE) for 25 elements from Li to Nd and for 18 of them by taking into account the departures from LTE (non-LTE). In \(\upsilon\) Aql, 21 Lyn, and \(\kappa\) Cep, which are classified as normal stars in the literature, the non-LTE abundances of the elements from He to Fe are indeed consistent with their solar values within 0.1 dex, but overabundances of Co, Ni, Zn, Sr, Y, Zr, and Ba relative to their solar abundances are observed and their values correlate with the stellar temperature \(T_{\textrm{eff}}\). Thus, we have confirmed the temperature dependence of the Zn, Sr, Y, Zr, and Ba overabundances revealed in our previous papers for normal stars and for the first time have found an analogous dependence for Co and Ni. HD 145788 with an overall overabundance of iron-group elements of 0.17 dex is at the initial stage of transformation into an Am star. The line profiles in the spectra of 7 Sex and 134 Tau suggest that these are rapidly rotating stars seen pole on, and their analysis requires using the methods that take into account the non-sphericity of the star.