An international team of researchers discovered that ancient stars were capable of producing elements with an atomic mass of more than 260. It is heavier than any element of the periodic table found on Earth in natural conditions.
According to Carl Sagan’s famous saying, we are literally made of stellar matter. All elements heavier than hydrogen and helium were synthesized during stellar evolution, either inside the bowels of the luminaries or during such catastrophic processes as supernova flares or neutron star mergers.
It is known that the heaviest elements are formed as a result of rapid neutron capture, or the so-called r-process. This is when an atomic nucleus captures numerous neutrons in a very short period of time. Due to this, elements like gold, platinum or uranium are born. At the same time, the heaviest elements are unstable and disintegrate over time.
The conditions described above can only occur if a huge amount of energy is released and numerous free neutrons are present. The best place to find both is at the birth or death of a neutron star, when such objects collide and produce raw materials for the r-process.
The problem is that scientists currently do not know many details of the r-process, including what the limit is on the number of neutrons that can be added to an atom.
To find answers to these questions, an international team of researchers estimated the amount of heavy elements in 42 well-studied stars in the Milky Way. They are known to contain heavy elements formed as a result of the r-process in previous generations of stars. By looking at the amount of each heavy element found in these stars collectively but not individually, scientists identified patterns that had previously eluded them.
These patterns indicate that some elements in the middle of the periodic table, such as silver and rhodium, are probably remnants of the separation of heavy elements. The team could determine that the r-process could produce atoms with an atomic mass of at least 260 before their subsequent decay. This is more than the atomic mass of uranium (238) and plutonium (244), the heaviest elements found on Earth in natural conditions.
According to https://phys.org
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