Other Fusion Reactions

As a star begins to exhaust its hydrogen fuel, it can use other methods to convert matter to energy.

The carbon-nitrogen-oxygen (CNO) cycle is most efficient at temperatures at or above 28,800,000°F. In this process carbon is used as a catalyst to promote conversion of hydrogen to helium.

At even higher temperatures, (180,000,000°F) helium can be converted to beryllium and then carbon in the following reactions:

⁴He + ⁴He ------> ⁸Be + g

⁸Be + ⁴He ------> ¹²C + g

These reactions pale in comparison to the reactions that fuse carbon into other heavy elements. These reactions do not occur until the core temperature of the star approaches 1,080,000,000°F. These reactions can fuse heavier nuclei into commonplace nuclei found on earth. Here is a diagram of some of these reactions:

These changes in available matter in the core and its effect on the core temperature affect the star overall. To see how this affects the star, go to the giant and supergiants page.

The next time you look up, just think, all of the matter you are made of came from stars having carbon fusion in their cores.