This award will provide continuing support for the Wisconsin Atomic Transition Probability (WATP) program. The project includes the completion of very precise and accurate transition probability measurements of Titanium. These measurements will include the very important weak lines with low excitation potential in Ti II. Such lines sample the majority of the titanium in the photospheres of stars. Similar measurements will subsequently be extended to cobalt, nickel, and vanadium. Emission branching fractions will be measured using available spectra from a Fourier transform spectrometer and new data from a recently developed 3 m focal length vacuum echelle spectrograph. Radiative lifetime measurements will be performed on atom/ion beams using a WATP program time-resolved laser induced fluorescence experiment. Systematic uncertainties on these iron-group measurements will be 5% or less with high confidence. Collaborating astronomers will apply this lab data to determine highly reliable relative iron-group abundances in (old) metal-poor stars.
The research effort will include the training of undergraduate and graduate students. The project is expected to aid in the interpretation of future large-scale spectroscopic surveys of metal-poor stars in the outskirts of the Milky Way.
