Thursday, 10 June 2010

Understanding the triple-alpha process

All nuclei heavier than lithium (atomic number 3) are made in stars. It's only pretty recently we've understood that and the confirmation that stars are giant nuclear reactors is one of the great stories of modern physics (which I will not tell here right now!) One of the stumbling blocks to realising that nuclear fusion happens in stars is that it seemed at first like there was no way helium nuclei could fuse to form anything, as they can't fuse with any single thing that's available in stars to make something stable.

The breakthrough was the realisation by Fred Hoyle that what must happen is that three helium nuclei must interact together to form carbon-12. This highly improbably process turns out to happen thanks to a resonance in carbon-12 just around the energy that is available when three helium nuclei meet inside stars. Without it, we would not be here. Some collaborators of mine have just published a really fantastic paper running simulations of this reaction and show how the alpha particles interact. It's available here and it takes the understanding of the process to a new microscopic level. Good work collaborators!


  1. Having never heard of the triple alpha process, I still find this very interesting. Very much enjoying my new education from your posts.

  2. As Paddy famously said, "the meaning of life is not 42. It's 92. As in, the 92 keV by which 8Be is unbound." :-)