Particles and forces important in the Sun

The three forces

electromagnetic.
- felt by all charged particles
- holds atoms together
- like charged particles repel
- oppositely charged particels attract
strong
- felt by protons and neutrons
- holds nuclei together
- strong but short ranged (~10^-15 m).
weak
- very weak
- short ranged
- felt by most particles
- responsible for important reactions in the Sun.

The particles we have to work with

proton
- heavy
- charge +1
- feels the strong force
neutron
- heavy
- charge 0
- feels the strong force
electron
- light
- charge -1
- does not feel the strong force
anti-electron
- light
- charge +1
- does not feel the strong force
photon
- mass 0 (so moves with speed of light)
- charge 0
- carries the electromagnetic force
neutrino
- mass almost 0
- charge 0
- does not feel the strong force
- does not feel the electromagnetic force
- interacts only with weak force.
- Hardly any interactions, so zips through matter easily.
- There are different kinds of neutrinos. This one is the electron neutino.
anti-neutrino
- mass almost 0
- charge 0
- does not feel the strong force
- does not feel the electromagnetic force
- interacts only with weak force.
- Hardly any interactions, so zips through matter easily.
- There are different kinds of neutrinos. This one is the anti-electron-neutino.

Nuclei

H nucleus
- (p) made of one proton
²H nucleus
- (pn) made of one proton and one neutron
³He nucleus
- (ppn) made of one proton and two neutrons
⁴He nucleus
- (ppnn) made of two protons and two neutrons

There are, of course, more kinds of nuclei. The scheme is that in ⁿA, the "n" tells the total number of protons and neutrons and the "A" tells how many protons: H, He, Li, Be, ... stand for 1,2,3,4,... protons. This goes up to U for 92 protons. The normal kind of uranium is ²³⁸U.

ASTR 122 course home page

Updated 11 October 2007

Davison E. Soper, Institute of Theoretical Science, University of Oregon, Eugene OR 97403 USA