Let us go step by step to get it right.
Helium is made in stars that have the approximate mass of Sun. But those star babies that are born with mass that is 1.5 times or more the mass of Sun do not burn with proton-proton chain making hydrogen directly from helium. Instead, they burn in carbon cycle so we have already in the picture some heavier atoms in the Universe, carbon, nitrogen and oxygen.
Professor Kaler explains the nuclear reaction:
[Carbon cycle] begins when
- a normal carbon atom (C-12, with 6 protons and 6 neutrons) picks up a proton to make radioactive nitrogen-13
- one of whose protons ejects a positron (positive electron) to make stable carbon-13 (with the additional ejection of a neutrino)
- Carbon-13 plus a proton makes normal nitrogen-14
- while an additional proton collision makes oxygen-15, which (like N-13) decays into nitrogen-15
- The N-15 collects another proton, and then falls apart into the original carbon-12 and a helium nucleus
Each event produces some energy either itself or through the collisions of positrons and electrons.
Ugh... this apparently is not as simple as atom plus minus a proton, electron, positron, neutron, catching, decaying... fusion, fission...
Indeed, in order to understand the making of iron in God's huge creations, the stars, we need to study those tiniest creations, atoms and their sub-particles. There is a fascinating harmony and order from micro-cosmos to macro-cosmos, isn't there!
BTW, from where do the greater mass stars get the normal carbon for the carbon cycle to work?