Feb 25, 2025 · CNO clearly stands for carbon-nitrogen-oxygen. In some cycles it can produce neon see CNO cycle (CNO IV). You also have the carbon-burning process (not to be confused with CNO) that produces neon by colliding two carbon atoms. The CNO cycle can take place even in hydrogen-core stars.

Jun 23, 2024 · It's not the fact that the carbon is regenerated that makes the CNO reactions faster than the P-P reaction. The reactions are faster simply because the cross sections are larger. The cross section for the P-P reaction is extremely small - so small that it is not measurable in the lab and has to be calculated.

Nov 20, 2021 · From what I understand, main sequence stars only fuse Hydrogen into Helium, and this is mainly due to the proton-proton chain or the CNO cycle. However, the CNO cycle requires a carbon catalyst. If these main sequence stars only fuse hydrogen into helium, how can the CNO cycle even take place if there isn't any carbon present?

Oct 22, 2016 · The CNO cycle does take place in the earliest massive stars, but only once a significant amount of helium has been burned into carbon by the triple alpha reaction. Massive population III stars ($>20 M_{\odot}$) cannot be supported on the "main sequence" by pp hydrogen burning alone. What happens is that they collapse until their cores become ...

Mar 23, 2015 · PP Chain and CNO cycle relationship. Ask Question Asked 10 years, 1 month ago. Modified 10 years, 1 month ago.

Nov 10, 2014 · There are several different CNO cycles which occur in stars of different masses. The various products in the CNO reaction chain occur at different times due to the fusion of a proton with a C or N nucleus, which then decays radioactively in one of several different ways. For more details on the various CNO cycles, see this article:

Mar 20, 2020 · Try calculating the bremsstrahlung losses from your plasma and compare that to the energy generated by the CNO cycle. I think you will find that it is a net loss. Unless your reactor is large enough that the bremmstrahlung radiation cannot escape (like in a star), your reactor will have net loss of energy.

Nov 25, 2018 · "In metal-free massive stars, the CNO cycle cannot be activated initially. Because the energy generation due to the pp [proton-proton] chain is too weak to support a massive star with M ≥ 20 MSun for a significant fraction of the evolutionary time, the stellar core rapidly contracts until enough carbon . . . is produced by helium burning . . . .

May 28, 2015 · The CNO cycle produces 4 He, 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.

Nov 21, 2014 · Specifically, the CNO cycle uses Carbon, Oxygen, an Nitrogen as catalysts for the reaction 4H->He, the "interesting" branches of the cycle are the ones which produces an alpha particle from 4 protons.