I Question about stellar nucleosynthesis from a non-expert

AI Thread Summary
The discussion centers on the production of uranium through stellar nucleosynthesis, particularly focusing on the role of supernovae and neutron star mergers. It is noted that uranium is primarily formed through the r-process, which can occur in supernovae, specifically during core collapse events. The minimum number of supernovae required to produce uranium is suggested to be one, as supported by sources like Wikipedia. Participants highlight that heavy elements are frequently observed in supernova spectra, indicating their formation during these explosive events. Overall, the conversation emphasizes the well-studied nature of supernovae and their contribution to the creation of heavy elements in the universe.
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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?
 
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Wow! That's quite remarkable. Thanks for your reply.
 
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?
 
It's probably right. Just not the question that was asked.
 
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, ..."
 
dtowne said:
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)?
 
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.
 
dtowne said:
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.
Except the hypothesis of Cf powering supernovae was not confirmed when checked, and it is now attributed to Ni-56 instead.
 
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