CNO cycle

Definition

The CNO cycle (Carbon-Nitrogen-Oxygen cycle) is a series of nuclear fusion reactions that occur in stars, where hydrogen is converted into helium using carbon, nitrogen, and oxygen as catalysts. It dominates in stars more massive than the Sun.

5 Must Know Facts For Your Next Test

1. The CNO cycle requires higher temperatures than the proton-proton chain reaction, typically above 15 million Kelvin.
2. It contributes to the energy production in stars with masses greater than 1.3 times that of the Sun.
3. In the CNO cycle, carbon acts as a catalyst and is regenerated at the end of the cycle.
4. The primary energy output of the CNO cycle comes from the conversion of hydrogen into helium.
5. The CNO cycle releases positrons and neutrinos along with energy in the form of gamma rays.

Review Questions

Related terms

Proton-Proton Chain:

A series of nuclear reactions by which stars convert hydrogen into helium at core temperatures below 15 million Kelvin

Stellar Nucleosynthesis:

The process by which elements are formed within stars through nuclear fusion reactions

Gamma Rays:

High-energy electromagnetic radiation released during nuclear reactions such as those in stellar cores