The True Origins of Gold in Our Universe May Have Just Changed, Again - ScienceAlert

When humanity finally detected the collision between two neutron stars in 2017, we confirmed a long-held theory - in the energetic fires of these incredible explosions, elements heavier than iron are forged.

According to new galactic chemical evolution models, neutron star collisions don't even come close to producing the abundances of heavy elements found in the Milky Way galaxy today.

"Neutron star mergers did not produce enough heavy elements in the early life of the Universe, and they still don't now, 14 billion years later," said astrophysicist Amanda Karakas of Monash University and the ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D) in Australia.

In the nuclear fusion furnaces of their cores, these stars forged hydrogen into helium; then helium into carbon; and so on, fusing heavier and heavier elements as they run out of lighter ones until iron is produced.

As stars age, they produce heavier and heavier elements as their insides heat up.".

But, in order to produce the quantities of these heavier elements we observe, we'd need a minimum frequency of neutron star collisions.

And, among their findings, they found the neutron star collision frequency lacking, from the early Universe to now.

"Even the most optimistic estimates of neutron star collision frequency simply can't account for the sheer abundance of these elements in the Universe," said Karakas.

They found that stars less massive than about eight solar masses produce carbon, nitrogen, fluorine, and about half of all the elements heavier than iron.

Stars more massive than eight solar masses produce most of the oxygen and calcium needed for life, as well as most of the rest of the elements between carbon and iron.