Abundances of Mn, Co and Eu in a sample of 20 F-G disk stars: The influence of hyperfine structure splitting

Abstract

We present Mn, Co and Eu abundances for a sample of 20 disk F and G dwarfs and subgiants with metallicities in the range -0.8 ≤ [Fe/H] ≤ +0.3. We investigate the influence of hyperfine structure (HFS) on the derived abundances of Mn and Co by using HFS data from different sources in the literature, as well as calculated HFS from interaction factors A and B. Eu abundances were obtained from spectral synthesis of one Eu II line that takes into account HFS from a series of recent laboratory measurements. For the lines analysed in this study, we find that for manganese, the differences between abundances obtained with different HFSs are no greater than 0.10 dex. Our cobalt abundances are even less sensitive to the choice of HFS than Mn, presenting a 0.07 dex maximum difference between determinations with different HFSs. However, the cobalt HFS data from different sources are significantly different. Our abundance results for Mn offer an independent confirmation of literature results, favouring type la supernovae as the main nucleosynthesis site of Mn production, in contrast to trends of Mn versus metallicity previously reported in the literature. For Co, we obtain [Co/Fe] ∼ 0.0 in the range -0.3