Once the hydrogen in the core of a star runs out, what element does the star begin to fuse next?
Okay, so in this question, we’re considering a star, which is actually powered by fusion reactions in its core. Now, towards the beginning of the star’s life, there is a lot of hydrogen present in the star’s core. This hydrogen then fuses together to form helium. And this process keeps on going until all of the hydrogen in the star’s core runs out.
At that point, all of the hydrogen has fused and all that’s left in the core now is helium. Once this happens, then the helium has no choice but to start fusing as well. Therefore, once all the hydrogen in the core of a star runs out, the next element to start fusing is helium.