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Naturally occurring elements heavier than U ?


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Is it possible that in a certain region of the galaxy there was a series of supernovas of massive stars, creating a second generation of massive stars that also went supernova after only hundreds of millions of years.  And this process continued more times than our solar system did.  Is it possible that matter that is heavier than uranium could have been created?  If there existed elements, in other solar systems, heavier than uranium, could we detect it?

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3 hours ago, Airbrush said:

Is it possible that in a certain region of the galaxy there was a series of supernovas of massive stars, creating a second generation of massive stars that also went supernova after only hundreds of millions of years.  And this process continued more times than our solar system did.  Is it possible that matter that is heavier than uranium could have been created?  If there existed elements, in other solar systems, heavier than uranium, could we detect it?

I think the problem is there are good reasons to expect such transuranic elements to be unstable and to decay fairly rapidly. So no matter how much was produced it would not last and would not be around to observe for long.  

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12 hours ago, Airbrush said:

Is it possible that in a certain region of the galaxy there was a series of supernovas of massive stars, creating a second generation of massive stars that also went supernova after only hundreds of millions of years.  And this process continued more times than our solar system did.  Is it possible that matter that is heavier than uranium could have been created?  If there existed elements, in other solar systems, heavier than uranium, could we detect it?

Matter heavier than U is undoubtedly created in these events, and mergers. But we’d have to detect it before it decayed away, as exchemist notes, unless there’s some method of continued production.

This has happened (We’ve had threads on this)

https://en.wikipedia.org/wiki/Przybylski's_Star

Przybylski's Star also contains many different short-lived actinide elements with actinium, protactinium, neptunium, plutonium, americium, curium, berkelium, californium, and einsteinium being detected.

 

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They should get created in such events as e.g. neutron star mergers - we just can't look for them.

This has several reasons:

First, transuranes are terribly unstable, with half-life in the millisecond range. (see below for some more...). Then, these unstable superheavy nuclei would decay into lighter nuclei, eventually ending up in one of the four possible decay series. (One of these, the Neptunium cascade, is technically extinct in earths natural element composition, as the half-life of its most stable isotope is in the million-years-range - while Earth has a few billion years of age)

So, unless you're thinking REALLY big, no chance that these nuclei are stable...

(...and thinking really big means atomic weights in the 10^57 range - Chandrasekar * Avogadro...   ...and these "atoms" are commonly known as "neutron stars". White dwarfs still have discernible elemental compositions AFAIK.)

 

Nuclear physics, however, predicts that at certain nucleic weigths with appropriate proton numbers, the nuclei should again be more stable. The best known is the element 110 island of stability. The wikipedia entry concerning that is quite good: https://en.wikipedia.org/wiki/Island_of_stability. As of now, we don't yet have the techniques to get those isotopes with the sufficent neutron numbers, though, but the less-stable isotopes that were generated did AFAIK mostly behave as predicted.

 

The question where trans-irons come from - after all, nuclear fusion kinda "stops" at iron - has been partially answered / demonstrated: The merger of neutron stars mentioned above. https://www.science.org/content/article/neutron-star-mergers-may-create-much-universe-s-gold

But beware, that case isn't closed yet, there's much ongoing debate: Look here for a more differentiated take: https://www.pnas.org/content/118/4/e2026110118.

 

Still, we know that NS mergers do generate heavy elements, and there's no reason that there should be a cap at somewhere around 100 Da. That superheavy stuff just tends to decay really, really fast...

Edited by Godot
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  • 2 weeks later...
On 11/14/2021 at 12:52 PM, Godot said:

First, transuranes are terribly unstable, with half-life in the millisecond range. (see below for some more...). Then, these unstable superheavy nuclei would decay into lighter nuclei, eventually ending up in one of the four possible decay series. (One of these, the Neptunium cascade, is technically extinct in earths natural element composition, as the half-life of its most stable isotope is in the million-years-range - while Earth has a few billion years of age)

So, unless you're thinking REALLY big, no chance that these nuclei are stable...

....

Nuclear physics, however, predicts that at certain nucleic weights with appropriate proton numbers, the nuclei should again be more stable. The best known is the element 110 island of stability. The wikipedia entry concerning that is quite good: https://en.wikipedia.org/wiki/Island_of_stability. As of now, we don't yet have the techniques to get those isotopes with the sufficent neutron numbers, though, but the less-stable isotopes that were generated did AFAIK mostly behave as predicted.

The question where trans-irons come from - after all, nuclear fusion kinda "stops" at iron - has been partially answered / demonstrated: The merger of neutron stars mentioned above. https://www.science.org/content/article/neutron-star-mergers-may-create-much-universe-s-gold

But beware, that case isn't closed yet, there's much ongoing debate: Look here for a more differentiated take: https://www.pnas.org/content/118/4/e2026110118.

Still, we know that NS mergers do generate heavy elements, and there's no reason that there should be a cap at somewhere around 100 Da. That superheavy stuff just tends to decay really, really fast...

Does this mean that elements heavier than uranium cannot live very long?

If there was a stable, long-lived element, heavier than uranium, somewhere in this galaxy, could we detect it?

Edited by Airbrush
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