A New Survey to Constrain the Astrophysical r-Process

There are presently some 35 highly r-process-element-enhanced metal-poor (r-II) stars known in the Galactic halo, roughly twenty-five years after their first recognition. These stars exhibit enhancements of their r-process-element to iron ratios, relative to Solar ratios, by a factor of 10 to 100+ ([r-element/Fe] > +1.0). Despite their very low metallicities ([Fe/H < –2.0), these stars exhibit an apparently universal [r-element/Fe] pattern that is very well-matched to the Solar     r-process pattern. As such, they have long been thought to provide fundamental information on the likely astrophysical site of the r-process.  A new large-scale effort to dramatically increase the numbers of recognized r-II stars (from ~35 to ~100-150) is now underway; current results will be reported on, including the identification of numerous new bright r-II and r-I stars, several of which have detectable U and Th, and new examples of stars that exhibit the actinide-boost phenomenon – and likely to be a key to understanding the nature of the r-process.