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The CNO ( carbon- nitrogen- oxygen) cycle is one of two fusion reactions by which stars convert hydrogen to helium, the other being the proton-proton chain.
While the proton-proton chain is more important in stars the size of the sun or less, theoretical models show that the CNO cycle is the dominant source of energy in heavier stars.
The CNO cycle may also be the dominant cause of nitrogen and oxygen production.
In actuality there is not only CNO cycle but three possible cycles which are astrophysically important. The main CNO cycle looks like this:
| 12C + 1H | → | 13N + γ |
| 13N | → | 13C + e+ + νe |
| 13C + 1H | → | 14N + γ |
| 14N + 1H | → | 15O + γ |
| 15O | → | 15N + e+ + νe |
| 15N + 1H | → | 12C + 4He |
The cycle results in the fusion of four hydrogen nuclei (1H, protons) into a single helium nucleus (4He, alpha particle), which supplies energy to the star in accordance with EinsteinAlbert Einstein ( March 14 1879 April 18 1955) was a theoretical physicist who is widely regarded as the greatest scientist of the 20th century. He proposed the theory of relativity and also made major contributions to the development of quantum mechanics's equation.
Ordinary carbon serves as a catalystEnthalpy profile for catalysed and uncatalysed reactions. A is the activation energy for an uncatalysed reaction, A is the reduced activation energy for the same reaction when catalysed. I represents the point at which a chemical intermediate has been for in this set of reactions and is regenerated.
See also
- Triple-alpha processThe triple alpha process is the process by which three helium nuclei ( alpha particles) are transformed into carbon. This nuclear fusion reaction can only occur rapidly at temperatures above 100,000,000 degrees and in stellar interior having a high helium
- Proton-proton chain
