Electron

Proton

Neutron

Nucleus

because proton capture is fast that an unstable nucleus may combine with another proton before undergoing decay

because neutron capture is fast that an unstable nucleus may combine with another neutron before undergoing decay

because proton capture is slow that an unstable nucleus may combine with a neutron before undergoing decay

because neutron capture is slow that an unstable nucleus may combine with a proton before undergoing decay

supernova

synthesis

speed

slow

alpha particle

beta particle

x-ray

gamma ray

$$^3H$$  

Tritium

$$^4He$$  

Helium-4

$$^1H$$  

Hydrogen

$$^3He$$  

Helium-3

Tritium

Deuterium

Helium-3

Helium-4

There were more protons than neutrons in the universe.

The nuclei combined with electrons to produce neutral atoms.

Helium nuclei outnumbered hydrogen nuclei in the universe.

The universe was filled with combined protons and electrons, with neutrons roaming freely in space.

Hydrogen

Nitrogen

Carbon

Helium

Neutron

Nucleus

Electron

Proton

because it initiates the first reaction

because it is the starting point of the cycle

because it does not participate in the cycle

because it is regenerated in the final step

proton-proton chain

carbon-nitrogen-oxygen cycle

triple alpha process

alpha process

$$^{52}Fe\ +\ \gamma$$  

$$^{48}Cr\ +\ \gamma$$  

$$^{36}Ar\ +\ \gamma$$  

$$^{20}Ne\ +\ \gamma$$  

$$_{28}^{60}Ni+2_0^1n\ \rightarrow\ _{29}^{62}Cu+_{-1}^0\beta$$  

$$^{12}C\ +\ \gamma$$  

$$_{29}^{62}Cu+_1^1p\ \rightarrow\ _{30}^{63}Zn$$  

$$_{24}^{48}Cr\ +\ _2^4He\ \rightarrow\ _{26}^{52}Cu$$  

Via Stellar Nucleosynthesis

Via Big Bang Nucleosynthesis

Via Stellar Evolution

Via Supernova

Cosmo Micro Background Radiation

Cosmic Microscopic Background Radioactive

Cosmic Microwave Background Radiation

Cosmos Microwave Background Radiation