Hydrogen to Helium...Helium to heavier elements

p.falk

Would someone mind (in simple terms if possible) explaining how at the beginning of the universe Hydrogen combined to give Helium; then then how Helium combined with deuterium to create the heavier elements?

I would just like to be more versed on this process...
Thanks for any help!!!!

russ_watters

Short answer: stars "burn" via nuclear fusion. Hydrogen atoms combine to form helium. As helium concentrations get higher, helium atoms fuse to form heavier elements. If the star goes supernova, the resulting explosion is powerful enough for endothermic fusion of heavier elements into really heavy elements.

p.falk

But I thought a Helium can't combine with another Helium atom because the result would be too unstable. If a Helium(2 protons/2neutrons) combines with a Helium you have 8 particles... but atoms with 5 or 8 particles are unstable.
That's why I wanted to know what role deuterium plays in this...
How is deuterium created? How long does it last on it's own? What are the steps from Hydrogen to Helium to heavier elements?

I appreciate your response russ_watters, I guess I would like some more detail with it though.
Thanks for helping...

Astronuc

The sun produces energy primarily by the PP reaction and about 1-2% by the CNO cycle. The CNO cycle occurs in more massive stars -

http://csep10.phys.utk.edu/astr162/l...gy/cno-pp.html
http://burro.astr.cwru.edu/Academics...s/ppchain.html
http://csep10.phys.utk.edu/astr162/lect/energy/cno.html - for CNO discussion

In addition to H and He, there are quantities of Li, Be and B, and they will be producing their emission spectra as well.

See also - Reaction Rates for Stellar Nucleosynthesis

and

Helium Burning in Stars

In the second link above, one will find