Question: Doesn't the sun also fuse two helium atoms into beryllium and then fuse the beryllium with another helium to produce carbon?

Josh Makepeace answered on 18 Jun 2013:

Hello, theantihiggs!

Great fusion knowledge! You’re exactly right, you can make heavier elements from fusion, too. In a star like our sun, most of the energy is produced by hydrogen atoms fusing to form helium. But, like you say, a small amount of the energy released is produced when two helium nuclei fuse together to form beryllium. That beryllium can also then react to form lithium.

In stars that are hotter than our sun, you can then get more fusion happening to make even heavier elements, like the carbon reaction you mentioned. These stars can also make elements like nitrogen, oxygen, sodium, magnesium and others all the way up to iron and nickel in the periodic table!

The really heavy elements need an extra boost of energy to form. So the main way that they can form is when a very old large star explodes in a supernova. The intense heat produced when one of these stars explodes is enough to produce all of the heavy elements.

So starts really are element-making factories! Thanks for the great question 🙂