There's Gold in Them Neutron Stars - or - Maybe Not

In summary: Summary:The conventional wisdom is that heavy elements are produced in supernova explosions. However, there are some doubts about this theory, and it is not clear how much material is actually produced in these events. Another theory suggests that neutron star collisions are the main source of these elements. However, there are some problems with this theory as well. There is also uncertainty about how common these events are. In addition, models used to study chemical evolution rely on theoretical yields which are often uncertain.
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TL;DR Summary
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.

But a new analysis has revealed a problem. 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.
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I am under the impression that the heavy elements are produced in supernova explosions.
 
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mathman said:
I am under the impression that the heavy elements are produced in supernova explosions.
My understanding is that that was the conventional wisdom for a long time but that recently the view has shifted to their being created mostly by neutron star collision explosions and by supernovae but to a lesser degree (lesser amount of the overall mass produced for each element)
 
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Hi,

there are issues difficult to understand and explain in both sources.

It is claimed that Neutron Star Mergers (NSM) are not the main source of r-process elements because of timing: there are r-process abundance pattern in metal-poor stars in the galactic halo, which are up to 12Gyears old. That means that there was a heavy element source already working between the Big Bang and the moment of formation of those stars. In principle, stars would need more than that to evolve to a neutron star and then collide. The other problem with NSM is the ejection mechanisms: it is not clear that the amount of ejected material is enough to explain everything.

On the other hand, supernova and core-collapse supernova may not reach the conditions to form heavy nuclei by neutron capture (ie, there are not enough neutrons). The current treatment of neutrino in simulations is very simplistic. These neutrinos decrease the neutron density (which is much lower than in NSM) and prevents the formation of the heaviest elements. Only under extreme conditions of high rotation speed and very intense magnetic fields (up to 1e10 - 1e12 T) in very massive stars it is possible to achieve a full r-process in a simulation. The problem here is the number of observations which support the existence of such massive stars...

As far as I know, all of these just rely on simulations.

These are astrophysical sites where r-process may take place. But there are other processes which can synthesize heavy elements, like p-process or s-process. The problem with s-process is that we can not measure at laboratory the reaction rates (the probability of capturing a neutron) for energies which are found in stars. So, one has to invent a model and extrapolate... so, this may be another uncertainty source, which is usually disregarded.

In addition, Galactic Chemical Evolution (GCE) models rely on theoretical/simulated yields which introduce a huge uncertainty, and GCE conclusions may be misleading.

Sorry this post increase the uncertainty instead of answering the OP

Regards,
ORF
PS: this meme summarizes this post
https://media.makeameme.org/created/uncertainty-uncertainty-everywhere.jpg
 
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It's okay, you have a point.
 

Related to There's Gold in Them Neutron Stars - or - Maybe Not

What is a neutron star?

A neutron star is a highly dense, compact star that is formed from the core of a massive star after it goes supernova. It is composed almost entirely of neutrons and has a diameter of only about 20 kilometers.

How is gold formed in neutron stars?

Gold is formed in neutron stars through a process called rapid neutron capture, or the r-process. This occurs when free neutrons are bombarded with other particles, causing them to rapidly combine and form heavier elements, including gold.

Is there really gold in neutron stars?

While the r-process does produce gold in neutron stars, it is still uncertain if there is enough gold present in these stars to be mined. Some studies suggest that there may be small amounts of gold in neutron stars, but it is not yet known if it is economically feasible to extract it.

Why is there debate about the existence of gold in neutron stars?

The debate about the existence of gold in neutron stars stems from the fact that it is difficult to observe and study these stars due to their extreme density and distance from Earth. Scientists are still working to gather more data and evidence to confirm the presence of gold in neutron stars.

What are the potential implications of finding gold in neutron stars?

If gold is found in large enough quantities in neutron stars, it could have significant implications for our understanding of the universe and the origins of heavy elements. It could also potentially open up new avenues for mining and resource acquisition in space.

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