# Fission in Sun

1. Nov 10, 2007

### spideyinspace

does the fusion reaction in sun produce neutrons or neutrinos? i read websites of which one is saying neutron is produced but the other one says neutrino is produced..which one is correct..what other things would be produced when hydrogen fuses to produce helium in the core of sun?

2. Nov 10, 2007

### Staff: Mentor

The principal fusion reaction in the sun is the proton-proton (pp) chain reaction.

http://csep10.phys.utk.edu/astr162/lect/energy/ppchain.html

some fusion takes place by the CNO-process
http://csep10.phys.utk.edu/astr162/lect/energy/cno-pp.html
http://hyperphysics.phy-astr.gsu.edu/hbase/astro/procyc.html

Neutrinos are produced in both reactions. It is possible that there are some p,n reactions which would produce neutrons, but that is not fusion.

zebu.uoregon.edu/~rayfrey/321/lecture5.pdf

http://star-www.dur.ac.uk/~afont/collision.html [Broken]

http://www.columbia.edu/~ah297/unesa/sun/sun-chapter4.html [Broken]

Last edited by a moderator: May 3, 2017
3. Nov 10, 2007

### spideyinspace

Thank you for all useful information...you said that some p,n reactions produce neutrons...can you give some information on that...i also found some fusion reactions in the lecture pdf which gives neutron..e.g 12c+12c gives 23Mg+n and 16O+16O gives 31S + n..so when some heavier elements than hydrogen and helium fuses, they do give out neutrons...so neutrons are also emitted from Sun..is this correct..what i mean is, which one is emitted from sun,neutrinos or neutrons?

Last edited by a moderator: May 3, 2017
4. Nov 10, 2007

### Staff: Mentor

require very high temperatures beyound those in the sun. Fusion of carbon is well beyond He fusion.

The p,n reaction has a fairly large energy threshold, particularly for light elements. I don't think n-production is significant in the sun. Certainly neutrino production is significant and neutrinos are emitted from the sun.

5. Nov 10, 2007

### D H

Staff Emeritus
One way to write the pp reaction is $6\;^1H \to ^4He + 2\;^1H + 2\beta + 2\gamma + 2\nu$. The helium-4 nucleus contains two neutrons. So in a sense, the proton-proton chain reaction process in the sun does create neutrons, but they are not free neutrons. They are instead bound with protons in the form of helium-4 nuclei.