What elements are produced in stellar nuclear fusion?

Stellar nuclear fusion primarily produces helium, but can also generate heavier elements up to iron.

In the heart of a star, nuclear fusion occurs, which is the process of combining lighter elements to form heavier ones. This process releases a tremendous amount of energy, which is what makes stars shine. The most common type of fusion in stars is hydrogen fusion, also known as the proton-proton chain. This process combines four hydrogen nuclei (protons) to form one helium nucleus (two protons and two neutrons), with the release of two positrons, two neutrinos, and a significant amount of energy.

However, stars don't just produce helium. As they age and their core temperature increases, they can start to fuse helium into even heavier elements. This process, known as helium fusion or the triple-alpha process, combines three helium nuclei to form one carbon nucleus. If the star is massive enough, it can continue this process to form elements up to iron.

The fusion of elements heavier than iron requires more energy than it releases, so it doesn't normally occur in stars. However, during a supernova - the explosive death of a massive star - the conditions are extreme enough for these heavier elements to form. This is how elements heavier than iron, such as gold and uranium, are created.

It's fascinating to think that all the elements we see around us, from the carbon in our bodies to the gold in our jewellery, were once created in the heart of a star. This process of stellar nucleosynthesis is a key part of our understanding of the universe and how it has evolved over billions of years.