Our very composition is a result of star processes. Stars serve as elemental factories where constant fusion and fragmentation of elements occur, leading to the creation of lighter or heavier elements. The categorization of elements as light or heavy is based on their atomic mass, determined by the number of protons and neutrons in the nucleus of an atom of that element.
The heaviest elements are typically formed in neutron stars through a phenomenon known as the rapid neutron capture process (r-process). Imagine a lone atomic nucleus surrounded by a neutron-rich environment. In a rapid timespan, often less than a second, a multitude of neutrons rapidly attaches to the nucleus. These neutrons then undergo internal changes, transforming into protons, ultimately resulting in the formation of a heavy element such as gold, platinum, or uranium.
However, these heaviest elements are inherently unstable or radioactive, undergoing decay over time. One mechanism for this decay is through a process called fission, where the heavy nucleus splits into smaller components.
Ian Roederer, associate professor of physics at North Carolina State University and lead author of the research, explains the significance of the rapid neutron capture process (r-process) in creating elements beyond lead and bismuth. He emphasizes the need for a rapid addition of numerous neutrons, requiring substantial energy and neutron abundance. The most suitable conditions for this process are found during the birth or death of a neutron star or in the aftermath of neutron star collisions.
While there’s a general understanding of the r-process, Roederer points out that the process occurs under extreme conditions, and crucial aspects remain unclear. The researchers aim to address questions about the various sites in the universe capable of generating the r-process, how the process concludes, and the limits of neutron addition. To explore these inquiries, they focused on studying elements produced by fission in well-examined ancient stars.
The research team conducted a comprehensive analysis of heavy elements in 42 well-examined stars within the Milky Way. These stars had heavy elements formed by the r-process in preceding generations of stars. Rather than focusing on individual stars, the team took a collective perspective on the amounts of each heavy element across these stars. This broader view revealed previously unnoticed patterns, suggesting that certain elements, including silver and rhodium, found around the middle of the periodic table, likely resulted from heavy element fission. The team further determined that the r-process can generate atoms with an atomic mass of at least 260 before undergoing fission. The findings were published in the journal Science.
Ian Roederer notes the significance of the atomic mass 260, as it represents a weight that has not been previously observed in space or naturally on Earth, even in nuclear weapon tests. The detection of elements with this mass in space offers valuable insights for refining models and understanding the process of fission. This discovery could provide crucial information about the origin and formation of the diverse array of elements found in the universe.
Resources
- ONLINE NEWS North Carolina State University. (2023, December 7). Ancient stars made extraordinarily heavy elements, researchers find. Phys.org. [Phys.org]
- JOURNAL Roederer, I. U., Vassh, N., Holmbeck, E. M., Mumpower, M. R., Surman, R., Cowan, J. J., Beers, T. C., Ezzeddine, R., Frebel, A., Hansen, T. T., Placco, V. M., & Sakari, C. M. (2023). Element abundance patterns in stars indicate fission of nuclei heavier than uranium. Science, 382(6675), 1177-1180. [Science]
Cite this page:
APA 7: TWs Editor. (2023, December 8). Extremely Heavy Elements Originated from Ancient Stars, Researchers Reveal. PerEXP Teamworks. [News Link]
