Early Galactic Nucleosynthesis of Iron-Group Elements: New Spectroscopic Constraints

Metal-poor stars of the Milky Way halo hold the fossil records of the first burst of Galactic nucleosynthesis some 13 billion years ago. We have discovered stars in the halo that have very anomalous contents of light elements carbon, nitrogen, and oxygen. We have also found, and have spent much effort understanding, metal-poor stars that have extraordinary enhancements of the heaviest neutron-capture elements. But we have taken far less care in the determination of precise abundance ratios of the iron-group elements Sc to Zn. In this talk I will discuss recent significant advances in this area, combining the efforts of stellar spectroscopy, lab atomic physics, and massive star nucleosynthesis theory. We now can constrain iron-group element production very well - but unfortunately - for just one star with metallicity [Fe/H] ~ -2.2. We will talk about recently-completed work on this star, and show new data on a star with [Fe/H] ~ -3.0 that will lead to much more global statements about the birth of these elements in the early days of our Galaxy.