Scientists have analyzed the heavy element content of modern stars and discovered new patterns that can so far only be explained by the decay of even heavier elements. This suggests that ancient stars synthesized unusually heavy elements, much heavier than any natural elements found on Earth.
Stars are “factories” that produce elements. The heaviest nuclei are synthesized through the so-called fast neutron capture process, or R process. In this case, the nucleus of an element (e.g. iron) captures free neutrons around it. As long as there are enough free neutrons, growth will “outpace” decay and the nucleus will continue to gain mass. Scientists believe that this method formed many nuclei heavier than iron, and all nuclei heavier than bismuth (atomic mass 208.89). The problem with studying their number and diversity in the universe is that they are unstable and decay over time.
The conditions suitable for the R process, i.e. huge amounts of free neutrons and energy, only arise in the Universe during the merger, formation and “death” of neutron stars. “We have a rough understanding of how the fast neutron capture process occurs, but the conditions are extreme. How many types of events in the Universe could trigger the R process? We don’t know yet, we don’t know how it will end, and we can’t answer the question, for example, how many neutrons can we add? Or how heavy are such elements? To find answers to at least some of these questions, we need to split the cores of heavy elements in well-studied ancient stars. “We decided to investigate the abundance of elements produced by the pyrolyte,” said Professor Ian Roederer, lead author of the new study. in Physics from North Carolina State University (USA).
Together with his colleagues, he selected 42 stars in the Milky Way galaxy where some of the heavy elements produced by the rapid capture of neutrons had already been discovered. In this case, it was important that there was no evidence of the influence of other processes, such as slow neutron capture (S process). Scientists compiled data on the 31 heavy elements (atomic numbers 34 to 90) in its composition. The authors used results from 35 of his previous studies.
They discovered patterns in the distribution of several elements. The content of ruthenium, rhodium, palladium, silver (atomic number Z = 44-47, atomic mass – 99-100) correlates with the content of heavier elements (atomic number Z = 63-78, atomic mass 150 and above) To do. At the same time, their neighboring elements have no such correlation. The research results were published in the journal Science. Scientists have searched for other possible routes for the appearance of these correlated elements, but none can explain such high values, the authors write. But all these heavy elements can be explained by the fact that they were created during the decay of even heavier but less stable atomic nuclei, which in theory could be created by the rapid capture of neutrons.
They discovered distribution patterns for several elements. The content of ruthenium, rhodium, palladium, silver (atomic number Z = 44-47, atomic mass – 99-100) correlates with the content of heavier elements (atomic number Z = 63-78, atomic mass 150 and above) To do. . At the same time, adjacent elements have no such correlation. The research results were published in the journal Science. Scientists have searched for other possible routes for the appearance of these correlated elements, but none could explain such high values, the authors write. However, all these heavy elements can be explained by the fact that they were formed during the decay of even heavier but less stable atomic nuclei, which in theory could be formed by the rapid capture of neutrons.
source: https://www.science.org/doi/10.1126/science.adf1341