Carl Sagan famously said that “we are all star stuff”, meaning the atoms and molecules that make us up as people, as creatures, as beings were all created in the violent explosions of stars. But understanding just how some of those elements came about has been a challenge to researchers. In a new paper published in Nature Communications, a team of scientists has uncovered just how one major life-building element – carbon-12 – was produced in those stellar explosions.

First off, there are three isotopes of carbon. We know of carbon-14 as a radioactive isotope used in dating organic material. The other two isotopes are carbon-12 and carbon-13, both of which are stable isotopes, meaning they don’t decay. Of those two, carbon-12 makes up over 90% of the naturally occurring carbon in our universe.

And in the paper, the team explains how four alpha particles – helium-4 atoms that have two protons and two neutrons – can cluster and eventually stabilize and form caron-12. They used first principles in their calculations, which is neat because it means they didn’t add anything we didn’t already know. And it means it can be assigned as a homework problem for some graduate student. 

This is pure maths at its finest, and because it was rather complex maths, it took them over a decade to design the software and code and statistical learning techniques to crunch all the numbers.

Questions still remain about when and where the carbon-12 gets produced. Co-author James Vary is curious if these atoms come from the internal processes in stars or supernova explosions or even collisions between neutron stars. He notes: This nucleosynthesis in extreme environments produces a lot of stuff including carbon.

We look forward to seeing where this research goes in the coming years.

More Information

Iowa State University press release

“α-Clustering in atomic nuclei from first principles with statistical learning and the Hoyle state character,” T. Otsuka et al., 2022 April 27, Nature Communications