SIMBAD references

We have checked the consistency between the copper abundance derived in six metal-poor stars using ultraviolet (UV) Cu II lines, which are assumed to form in the local thermodynamic equilibrium (LTE), and UV Cu I lines, treated in the non-local thermodynamic equilibrium (NLTE). The stars in our programme cover the atmospheric parameters that are typical for intermediate temperature dwarfs: the effective temperature is in the range of approximately 5800-6100 K, the surface garvity is from 3.6 to 4.5 and the metallicity is from about -1 to -2.6 dex. We have obtained good agreement for the abundances from these two sets of lines, and this demonstrates the reliability of our NLTE copper atomic model. We confirm that no underabundace of this element is seen at low metallicities: the mean [Cu/Fe] value is about -0.2 dex while, as follows from previous LTE studies, copper behaves as a secondary element and the [Cu/Fe] ratio in the range of [Fe/H] from -2 to -3 dex should be about -1 dex. According to our NLTE data, copper behaves as a primary element in the low-metallicity regime. We also conclude that our new NLTE copper abundance in metal-poor stars requires significant reconsideration of this element's yields in explosive nucleosynthesis.