A Fresh Look at Abundances of Iron-group Elements in Very Metal-Poor Stars
Studies of very metal-poor stars have focused attention on the neutron-capture (Z > 30) elements, whose dramatic star-to-star variations give us insights to element production in extreme, explosive nucleosynthesis environments. Neglected in this fascinating exotic element concentration is that the Fe group (Z = 21-30) often have inadequate abundances to say much of anything useful to massive star evolution theorists. Major improvements are ongoing in treatment of radiative transfer and stellar atmosphere structure. But these modeling improvements will completely wasted if the basic atomic data cannot be trusted. Jim Lawler's Wisconsin atomic physics group is nearly completion of lab work on neutrals and first ions of nearly all of the Fe-group elements. This talk will describe them and show how they are being used to overturn prevailing notions of early synthesis of the most abundant heavy elements in our Galaxy.