Helium Fusion, How Carbon is Made, and the Triple Alpha Process.
@chemistry-official asked me to make a post on how Carbon is created, so here goes:
This process uses the helium in a star’s core. For a refresher on how helium is made, click HERE for a detailed explanation and HERE for a simpler version.
As stars fuse hydrogen into helium, they eventually run out of hydrogen in their core to fuse. When the core is 100% helium, the star begins to collapse, since the outward push from fusion (which balances the inward pull of gravity) is no longer active. The star’s collapse heats up the core until the helium begins to fuse. The helium begins fusing very rapidly, and we call this the helium flash. It’s quite literally a flash too - the star’s brightness rapidly increases. The heat from this reaction heats up the outer layers of the star, which are made of hydrogen, which then begin to undergo proton-proton fusion to create helium.
Below is the reaction that occurs, turning helium into carbon:
This is how Carbon is formed - two helium nuclei combine to form Beryllium, followed by a third Helium fusing with the Beryllium to create Carbon. It’s called the triple-alpha process because this process uses three Helium nuclei, which are also called alpha particles. This process also releases energy, since Carbon nuclei are more stable than Helium nuclei. Since energy is released, the inward pull of gravity is then counteracted by the outward push from fusion, so the star is stable again.