Iron-peak Element Abundances in Warm Very Metal-poor Stars

Abstract We have derived new detailed abundances of Mg, Ca, and the Fe-group elements Sc through Zn ( Z = 21−30) for 37 main-sequence turnoff very metal-poor stars ([Fe/H] ≲−2.1). analyzed Keck HIRES optical near-UV high signal-to-noise spectra originally gathered a Be abundance survey. Using typically ∼400 lines with accurate laboratory transition probabilities each star, we determined LTE metallicities ratios neutral ionized species 10 as well α Mg Ca. find good neutral/ion agreement six that detectable transitions both in our 3100–5800 Å range. Earlier reports correlated Sc−Ti−V relative overabundances are confirmed, appear to slowly increase decreasing metallicity. To this element trio add Zn; it also appears be increasingly overabundant lowest-metallicity regimes. Co mimic behavior Zn, but issues surrounding its reliability cloud interpretation.