Hydrogen to Helium Helium to heavier elements

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Discussion Overview

The discussion revolves around the processes of nuclear fusion that lead to the formation of helium from hydrogen and the subsequent creation of heavier elements in stars. Participants seek to understand the mechanisms involved, including the role of deuterium and the conditions under which these reactions occur.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants explain that stars "burn" hydrogen via nuclear fusion to form helium, and as helium concentrations increase, helium can fuse to create heavier elements.
  • One participant questions the stability of helium atoms combining, noting that a combination of two helium atoms results in an unstable configuration with eight particles.
  • There is a request for clarification on the role of deuterium in the fusion process and inquiries about its creation and stability.
  • Another participant mentions that the sun primarily uses the proton-proton (PP) chain reaction for energy production, with a smaller contribution from the carbon-nitrogen-oxygen (CNO) cycle, which occurs in more massive stars.
  • References to external resources are provided for further reading on the PP chain and CNO cycle, as well as the production of lithium, beryllium, and boron in stars.

Areas of Agreement / Disagreement

Participants express varying levels of understanding regarding the fusion processes and the stability of resulting elements. There is no consensus on the specifics of how helium combines with other elements or the role of deuterium, indicating ongoing debate and exploration of these concepts.

Contextual Notes

The discussion includes unresolved questions about the stability of certain atomic configurations and the specific steps in the fusion process from hydrogen to heavier elements. The role of deuterium and its properties remain unclear among participants.

p.falk
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Would someone mind (in simple terms if possible) explaining how at the beginning of the universe Hydrogen combined to give Helium; then then how Helium combined with deuterium to create the heavier elements?

I would just like to be more versed on this process...
Thanks for any help!
 
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p.falk said:
Would someone mind (in simple terms if possible) explaining how at the beginning of the universe Hydrogen combined to give Helium; then then how Helium combined with deuterium to create the heavier elements?

I would just like to be more versed on this process...
Thanks for any help!
Short answer: stars "burn" via nuclear fusion. Hydrogen atoms combine to form helium. As helium concentrations get higher, helium atoms fuse to form heavier elements. If the star goes supernova, the resulting explosion is powerful enough for endothermic fusion of heavier elements into really heavy elements.
 
But I thought a Helium can't combine with another Helium atom because the result would be too unstable. If a Helium(2 protons/2neutrons) combines with a Helium you have 8 particles... but atoms with 5 or 8 particles are unstable.
That's why I wanted to know what role deuterium plays in this...
How is deuterium created? How long does it last on it's own? What are the steps from Hydrogen to Helium to heavier elements?

I appreciate your response russ_watters, I guess I would like some more detail with it though.
Thanks for helping...
 
The sun produces energy primarily by the PP reaction and about 1-2% by the CNO cycle. The CNO cycle occurs in more massive stars -

http://csep10.phys.utk.edu/astr162/lect/energy/cno-pp.html
http://burro.astr.cwru.edu/Academics/Astr221/StarPhys/ppchain.html
http://csep10.phys.utk.edu/astr162/lect/energy/cno.html - for CNO discussion

In addition to H and He, there are quantities of Li, Be and B, and they will be producing their emission spectra as well.

See also - http://www-phys.llnl.gov/Research/RRSN/

and

Helium Burning in Stars

In the second link above, one will find
ppchain.gif
 
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