The magazine “Science” reported that scientists have found, in samples from the ocean crust, on isotopes of plutonium and iron that do not form in terrestrial conditions.
The researchers thought that this indicated that a stream of volatiles from supernova explosions or merging neutron stars reached the surface of the Earth periodically.
The nuclei of chemical elements heavier than iron are thought to form in the stellar environment as a result of the nuclear process of sequentially capturing neutrons and creating increasingly heavy nuclei.
About half of the heavy nuclides form slowly as a byproduct of continuous stellar fusion, while the other half, especially all actinides, is observed to arise during the rapid capture of neutrons.
The scientists reproduced the process of rapid capture of neutrons in laboratory conditions, but they did not specify how it occurred in space.
At the present time, there are two hypotheses about this result, which is that it appears either as a result of explosions of certain types of supernovae or when merging neutron stars.
The study authors argue that this discovery provides an opportunity to take a fresh look at the astrophysical origin of the heavy chemical elements.