Searching for the First Stars Through Nuclear Reactions

Over the years, the interplay between nuclear physics, computational astrophysics, and observational astronomy has been critical to our understanding of the cosmos. Nuclear data and astrophysical models continue to provide key input to help explain and guide astronomical observations. Once recent example involves the search for the first generation of stars in the galaxy, which is predicted to have a rather unique chemical abundance signature compared to later generations of stars whose composition has been enriched with heavy metals. The predicted chemical abundance patterns depend sensitively on available nuclear data among other factors. One important nuclear reaction is the fusion of two carbon nuclei into a magnesium nucleus and a free neutron. In the past, many astrophysical models simply ignored this reaction because the available rate estimates were so uncertain. Now, however, a precise measurment of this reaction at astrophysical conditions has finally been provided using a laboratory accelerator. With the new measurement, it is found that this reaction is critical to the production of elements with odd atomic numbers (e.g. sodium, Z=11) in the first stars while also important to heavy-element synthesis in later stellar generations.

Speaker: Brian Michael Bucher, Lawrence Livermore Labs