John Cowan, an emeritus professor in astronomy and astrophysics at the University of Oklahoma, contributed to a paper recently published in the journal Science that finds ancient stars made extraordinarily heavy elements. The international team of researchers showed that ancient stars could produce elements with atomic masses greater than 260, heavier than any element on the periodic table found naturally on Earth.
"We still do not know much about the earliest history of our galaxy, formed relatively soon after the Big Bang. In particular, we do not know what types of stars or objects created the heaviest elements, which might include radioactive elements heavier than uranium," Cowan said.
Stars form almost all of the elements in the universe. The heaviest elements are radioactive, meaning they decay over time. One way that they do this is by splitting, a process called fission. These heavy elements would have radioactively decayed due to fission to form lighter, stable elements such as silver and palladium.
"This new work has found increases in the abundances of certain heavy elements, like silver and palladium, in a number of the most ancient stars in the Milky Way. This represents one of the first observations that indicate that some of those first stars did indeed produce radioactive elements heavier than uranium. This new result will help us better understand the formation of heavy elements in the earliest history of our galaxy and the universe," Cowan said.
The paper, "Element abundance patterns in stars indicate fission of nuclei heavier than uranium," was published in Science on Dec. 7, 2023, and was supported in part by the National Science Foundation and the National Aeronautics and Space Administration. Ian U. Roederer, North Carolina State University, is the corresponding author. DOI:10.1126/science.adf1341
