https://en.wikipedia.org/wiki/Beryllium wrote:
<<Both stable and unstable isotopes of beryllium are created in stars, but the radioisotopes do not last long. It is believed that most of the stable beryllium in the universe was originally created in the interstellar medium when cosmic rays induced fission in heavier elements found in interstellar gas and dust. Primordial beryllium contains only one stable isotope,
9Be, and therefore beryllium is a monoisotopic element.
Radioactive cosmogenic
10Be is produced in the atmosphere of the Earth by the cosmic ray spallation of oxygen.
10Be accumulates at the soil surface, where its relatively long half-life (1.36 million years) permits a long residence time before decaying to boron-10. Thus,
10Be and its daughter products are used to examine natural soil erosion, soil formation and the development of lateritic soils, and as a proxy for measurement of the variations in solar activity and the age of ice cores. The production of
10Be is inversely proportional to solar activity, because increased solar wind during periods of high solar activity decreases the flux of galactic cosmic rays that reach the Earth. Nuclear explosions also form
10Be by the reaction of fast neutrons with
13C in the carbon dioxide in air. This is one of the indicators of past activity at nuclear weapon test sites. The isotope
7Be (half-life 53 days) is also cosmogenic, and shows an atmospheric abundance linked to sunspots, much like
10Be.
8Be has a very short half-life of about 7×10
−17 s that contributes to its significant cosmological role, as elements heavier than beryllium could not have been produced by nuclear fusion in the Big Bang. This is due to the lack of sufficient time during the Big Bang's nucleosynthesis phase to produce carbon by the fusion of
4He nuclei and the very low concentrations of available beryllium-8. The British astronomer Sir Fred Hoyle first showed that the energy levels of
8Be and
12C allow carbon production by the so-called triple-alpha process in helium-fueled stars where more nucleosynthesis time is available. This process allows carbon to be produced in stars, but not in the Big Bang. Star-created carbon (the basis of carbon-based life) is thus a component in the elements in the gas and dust ejected by AGB stars and supernovae (see also
Big Bang nucleosynthesis), as well as the creation of all other elements with atomic numbers larger than that of carbon.>>