Understanding the CNO Cycle: Exploring the Accuracy of a Commonly Shared Video

In summary, the conversation discusses the CNO cycle and its relation to the production of helium. The CNO cycle involves nitrogen rather than neon and can also involve intermediate stages of neon at high temperatures. The picture in question is not representative of the CNO cycle and may be referring to the triple alpha process, carbon burning process, and neon burning process.
  • #1
Stephanus
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Dear PF Forum,
StellarNucleoSynthesis1.JPG

Is this picture correct?
Or it is not CNO Cycle?
I get that video from this
Thanks for any answer
 
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  • #2
The CNO cycle involves nitrogen rather than neon.
 
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  • #3
Vagn said:
The CNO cycle involves nitrogen rather than neon.
Yep, I think it makes more sense.

Carbon -> Nitrogen -> Oxygen
12 -> 14 -> 16
But I've seen it twice if not three times on youtube on diferent videos.
So perhaps what they actually mean is alpha process?
Carbon + He4 -> Oxygen
Oxygen + He4 -> Neon?

Thanks

Steven
 
  • #4
Stephanus said:
Yep, I think it makes more sense.

Carbon -> Nitrogen -> Oxygen
12 -> 14 -> 16
But I've seen it twice if not three times on youtube on diferent videos.
So perhaps what they actually mean is alpha process?
Carbon + He4 -> Oxygen
Oxygen + He4 -> Neon?

Thanks

Steven
The CNO cycle produces 4He, not consumes it. There are intermediate stages involving neon in some variations of the CNO cycles, but these only occur at very high temperatures. The basic cycle is carbon>nitrogen>oxygen>carbon, the full reaction is given on the CNO cycle wiki page.
 
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  • #5
Stephanus said:
Is this picture correct?
Or it is not CNO Cycle?

That picture is not the CNO cycle, which, as Vagn pointed out, converts hydrogen to helium in a multi-step process.

Stephanus said:
So perhaps what they actually mean is alpha process?
Carbon + He4 -> Oxygen
Oxygen + He4 -> Neon?

Actually I think the picture is referring to the triple alpha process, then the carbon burning process, and then the neon burning process.

http://en.wikipedia.org/wiki/Triple-alpha_process
http://en.wikipedia.org/wiki/Carbon-burning_process
http://en.wikipedia.org/wiki/Neon-burning_process
 
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What is the CNO Cycle?

The CNO Cycle, or the carbon–nitrogen–oxygen cycle, is a nuclear fusion process that occurs in the cores of stars in order to produce energy. It involves the fusion of hydrogen nuclei to form helium, with carbon, nitrogen, and oxygen serving as catalysts.

How does the CNO Cycle work?

In the CNO Cycle, hydrogen nuclei (protons) are fused together to form helium nuclei. This process releases energy in the form of gamma rays. The carbon, nitrogen, and oxygen nuclei act as catalysts, helping to facilitate the fusion reaction.

What is the significance of the CNO Cycle?

The CNO Cycle is one of the main processes by which stars produce energy. It is responsible for the majority of energy production in stars that are more massive than the sun. Without the CNO Cycle, these stars would not be able to sustain their energy output and would eventually die.

How is the CNO Cycle different from the proton-proton chain?

Both the CNO Cycle and the proton-proton chain are nuclear fusion processes that occur in stars. However, the CNO Cycle is more efficient and occurs in stars that are more massive than the sun. The proton-proton chain, on the other hand, is the primary source of energy production in smaller stars like the sun.

Can the CNO Cycle occur in all stars?

The CNO Cycle can occur in stars that are more massive than the sun, as it requires high temperatures and pressures that can only be sustained by these larger stars. However, it is not the only process by which stars produce energy. Smaller stars use the proton-proton chain, while even more massive stars may use different fusion processes altogether.

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