I Question about stellar nucleosynthesis from a non-expert

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CPW

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Given that the universe is 13.8 billion years old and our solar system is 4.6 billion years old, less than 10 billion years of star birth, life, and death is necessary to produce the heaviest occurring natural elements. Given what we know about supernova, what is the minimum number of supernova required to produce the element uranium?
 

Vanadium 50

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CPW

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Wow! That's quite remarkable. Thanks for your reply.
 

Drakkith

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Reading the wikipedia article about the r-process leades me to believe that uranium is mostly produced by merging neutron stars, not core collapse supernovae. Anyone have any comments about this?
 

Vanadium 50

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It's probably right. Just not the question that was asked.
 
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Looks like the answer is in fact 1, as mentioned above. Rationale, from Wikipedia:

"The creation of free neutrons by electron capture during the rapid collapse to high density of a supernova core along with quick assembly of some neutron-rich seed nuclei makes the r-process a primary nucleosynthesis process, meaning a process that can occur even in a star initially of pure H and He, ..."
 
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Looks like the answer is in fact 1, as mentioned above. Rationale, from Wikipedia:

"The creation of free neutrons by electron capture during the rapid collapse to high density of a supernova core along with quick assembly of some neutron-rich seed nuclei makes the r-process a primary nucleosynthesis process, meaning a process that can occur even in a star initially of pure H and He, ..."
Is there any evidence that this actually happens?
As in, r-process elements actually observed in supernova spectrum, and elements plainly showing they are newly formed (past curium)?
 
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Yes, heavy elements show up in supernova spectra all the time. Basically the first search result that I got was http://adsabs.harvard.edu/full/1956PASP...68..296B, and I know I've seen others.

Whether or not those are stars that were initially "pure H and He" I don't know, but there's a reasonable probability you could find out if you dig. There's lots of information on this; supernova are rather well studied.
 
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