n0

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n0
p
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Solar
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Big Bang nucleosynthesis Most of the raw
materials n0, p, e-, H and He (1H, 2H (D), 3He,
and 4He), along with a little tiny bit of Li,
Be So how do we get the rest of the elements?
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2H 3H -gt 4He n E
2.01355 u 3.01605 -gt 4.00260 u 1.00866 u ...
5.02960 u
5.01126 u
Dm 0.01834 u
1 u 1/NA g
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this nuclear fusion reactor can only fuse
elements deep in its core, and it cant create
anything heavier than He...
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our sun
stellar nucleosynthesis
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stellar nucleosynthesis produces elements UP TO
Fe, but no further making heavier elements is
endothermic, instead of exothermic... So how do
we get elements heavier than Fe?
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s-process this gets us only elements on the
neutron-poor side of the chart of the nuclides...
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r-process this gets us elements on the
neutron-rich side of the chart of the nuclides...
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zoom in on this region
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the abundance of O, Mg, Si, Fe nothing stable
higher than Bi
the abundance of 16O, 24Mg, 28Si, 56Fe and magic
neutron numbers 82 and 126
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• Summary so far
• Sun is 99.8 of solar system mass, so provides
  estimate of bulk composition
• Elemental and nuclear abundances reflect 5 main
  processes of nucleosynthesis (and explain
  abundance patterns)
• big bang p, n, H, He, a little Li
• stellar fusion up to Fe
• stellar n-irradiation s-process
• supernovae r-process
• galactic nucleosynthesis
• radioactive decay/production
• beta decay
• electron capture decay
• alpha decay
• fission

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• H and He are most of everything in the universe
  big bang nucleosynthesis
• Li, B, Be easily burned in starts most of it is
  from galactic nucleosynthesis
• more even than odd Z elements artifact of fusion
  and neutron capture-cross sections
• more light than heavy elements fusion is easy at
  low masses
• peak in abundance near Fe binding energy highest
  there stars cant do fusion at higher masses
• Tc, Pm gaps nothing stable
• magic numbers for r and s processes lead to peaks
  in high mass range

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• nuclides with A divisible by 4 are more abundant
  because of 4He burning
• Fe peak