Hydrogen and helium are the basic elements that make up the Universe. Nuclear synthesis in early Universe stopped at H, 4He, 3He, D, T, 7Li, and insignificant addition of heavier elements. Therefore, all elements starting from carbon are formed as a result of thermonuclear burning of the stars' substances, and upon explosions of supernovas, where elements up to 56Fe are sometimes formed. These heavy elements enter interstellar medium. Stars enriched by heavy elements are formed. Our Sun is a typical representative of such stars: it is quite rich in iron and other heavy elements.
This model illustrates certain nuclear reactions that occur in stars at the later stages of their evolution. Press "Run" button and observe any of the three reactions (triple alpha-process, photodissociation of iron, and substance neutronization) in the main display window. Reaction formulas are displayed in the lower window. Select the desired process with an appropriate switch. Pressing "Stop" button will suspend the animation. Press "Reset" to return the model to its initial state.
Protons and antiprotons are depicted as big red and blue balls, neutrons are gray balls, electrons and positrons as small blue and red balls, electron neutrinos are white, and photons are designated as yellow balls.
Triple alpha-process is actually a two-stage process. The current stage is outlined in red.