The Fission Fragments in Our Stars

The rapid neutron capture ("r") process is able to access the heaviest elements on and possibly beyond the periodic table. These massive elements are expected to undergo fission, though such heavy elements are poorly understood, if not inaccessible to modern experimental techniques. Meanwhile, without experimental data, theoretical models of these elements remain unconstrained. In this talk, I present an alternative piece of evidence that may be used to understand the behavior of heavy, fissile elements: the abundance patterns of metal-poor stars. Metal-poor stars encode the nucleosynthetic history of r-process events in the distant past, including possibly the earliest supernovae and neutron star mergers. We have found correlations of overabundances of r-process elements in these abundance patterns between elements with mass numbers A=99-110 and those with A>150 (but not A=110-150). I will discuss how we believe these overabundances are indicative of two primary fission fragments of transuranium elements with A>260 that are produced in r-process events and how metal-poor stars provide invaluable constraints on both theoretical and experimental data. However, stars are not the only astronomical sources of heavy-element data; I will also discuss a possible method of detecting the presence of transuranic elements in the kilonovae that proceed neutron star merger events. Between quiescent stars, multi-messenger observations, current theoretical models, and upcoming experiments, we may be able to understand properties of the most exotic nuclei that may exist in nature.