Astrophysics (Index)About

triple alpha process

(helium burning)
(fusion reaction chain turning helium-4 into carbon)

The triple alpha process (helium burning) is a fusion reaction in stars turning helium into carbon. This happens in older stars with abundant helium when the core collapses enough to produce sufficient temperature. Helium fuses into beryllium-8 which then fuses with another helium atom to produce carbon.

4    4     8
 He + He -> Be (-93.7 keV)
2    2     4

8    4     12
 Be + He ->  C (+7.367 MeV)
4    2      6

At about 100 million K, helium fuses faster than beryllium-8 decays and this process becomes significant. When this occurs, there is carbon to fuse with helium into oxygen.

Further reading:

Referenced by pages:
asymptotic giant branch (AGB)
alpha process
carbon (C)
carbon burning
horizontal branch (HB)
hydrogen burning
helium burning
nuclear energy generation rate (ε)
red clump (RC)