Nucleosynthesis and observation of the heaviest elements

The rapid neutron capture or r process' of nucleosynthesis is believed to be responsible for the production of approximately half the natural abundance of heavy elements found on the periodic table above iron (with proton number Z = 26) and all of the heavy elements above bismuth (Z = 83). In the course of creating the actinides and potentially superheavies, the r process must necessarily synthesize superheavy nuclei (those with extreme proton numbers, neutron numbers or both) far from isotopes accessible in the laboratory. Many questions about this process remain unanswered, such as where in nature may this process occur?' and what are the heaviest species created by this process?' In this review, we survey at a high level the nuclear proper-ties relevant for the heaviest elements thought to be created in the r process. We provide a synopsis of the production and destruction mechanisms of these heavy species, in particular the actinides and superheavies, and discuss these heavy elements in relation to the astrophysical r process. We review the observational evidence of actinides found in the Solar system and in metal-poor stars and comment on the prospective of observing heavy-element production in explosive astrophysical events. Finally, we discuss the possibility that future observations and laboratory experiments will provide new information in understanding the production of the heaviest elements.

Automated summary

The rapid neutron capture or r process is responsible for producing half of the heavy elements above iron and all of the heavy elements above bismuth. Despite many unanswered questions, this review provides an overview of the nuclear properties relevant to the heaviest elements created in the r process, including the actinides and superheavies. It also discusses observational evidence, such as the presence of actinides in the Solar system, and the potential for future observations and experiments to enhance our understanding of heavy-element production.