Origin of Elements and Nucleosynthesis
Clues from the heaviest elements and their isotopes
The quest to understand the origin of chemical elements has long captivated both scientists and philosophers. Modern astrophysics reveals that the first elements—hydrogen, helium, and traces of lithium—were formed just minutes after the Big Bang. All heavier elements, as well as additional helium and lithium, were synthesized through the life cycle of stars, with some being produced in later stages via processes such as supernovae, stellar winds, and mergers. Despite significant progress, questions remain regarding the specific stellar types and evolutionary stages in which these processes occur. One such example is the production of elements heavier than iron, which are formed through neutron-capture reactions. The main neutron-capture processes are the slow (s-) and rapid (r-) processes, depending on whether the timescale for neutron capture is slower or faster than that for radioactive beta decay. However, an additional intermediate (i-) process might operate at different metallicities. The isotopic signatures left by these neutron-capture processes differ, providing unique markers that can help distinguish between them. With its high resolution, multi-object capabilities, and access to relatively blue wavelengths, HRMOS is poised to significantly enhance our understanding of neutron-capture nucleosynthesis in the early Galaxy. By providing extremely precise measurements of heavy-element abundances and, in some cases, isotopic ratios, HRMOS will offer invaluable insights into these nucleosynthetic processes, surpassing the capabilities of medium-resolution spectroscopy.