Speaker
Description
How to make gold and silver? -The long-sought-after answer to this question remains one of the most challenging open problems that tie together nuclear physics with astronomy. Heavy elements like gold and silver are produced in the so-called rapid neutron-capture process (r-process). This process only occurs in rare explosive events in the Universe like supernovae (SNe) and neutron star mergers (NSMs), making it hard for astronomers to gather direct observations of the element creation. Likewise, it is difficult for nuclear physicists to recreate and study the nuclear process in the laboratory. These obstacles are why we today, six decades after the theoretical prediction of the r-process, still do not know how or at which astrophysical sites gold and silver are made. However, in 2016 the R-Process Alliance (RPA) initiated a successful new search to uncover bright metal-poor halo stars with r-process element enhancements. These stars are excellent laboratories for studying the r-process as the gas from which these stars formed was polluted by at most a few enrichment events --- perhaps even a single explosion. To date, the RPA has collected spectra of ~2000 stars and discovered over 70 new highly r-process enhanced. I will report on RPA efforts over the past six years and plans for the future, including ways this stellar sample can help constrain the astrophysical site(s) of the r-process.
