Hypernova outbursts in the early stages of the Milky Way galaxy’s existence could have been a source of elements for the r-process. It was during this process that heavy elements were synthesized – gold, platinum, uranium, zinc, and more.
Australian scientists have studied the star SMSS 2003-1142. It is a red giant located in a galactic halo 7,500 light-years from Earth. The star turned out to be poor in elements heavier than hydrogen and helium. But with an overall low metallicity, the star is enriched with elements such as zinc, barium, europium, and thorium, which are produced during the r-process.
The r-process itself or the fast process of neutron capture is the process of the formation of heavier nuclei from lighter ones by sequential capture of neutrons in the course of reactions.
In the r-process, atomic nuclei quickly capture neutrons, and many heavy elements are formed. It is assumed that the process takes place mainly during the mergers of neutron stars. However, such mergers alone do not explain the observed picture of the abundance of elements in low-metallicity stars. Scientists suggest that other conditions must exist in the Universe for the r-process to occur.
The analysis showed that the ratio of elements in the star SMSS 2003-1142 is consistent with the hypernova explosion model. The new study confirms the hypothesis that hypernovae were important sources of elements for the r-process in the very early stages of the formation of galaxies, including the Milky Way.
Recall that a hypernova is an explosion of a supermassive star after the collapse of its core; the collapse of the nucleus occurs after it runs out of fuel to support thermonuclear reactions. In fact, this is a very large supernova.