Nucleosynthesis

• Types of nucleosynthesis


  • Big Bang nucleosynthesis
  • Stellar nucleosynthesis
  • Supernova nucleosynthesis
• Big Bang nucleosynthesis


  Formation of elements in the early universe, about 3 minutes after the Big Bang
• Big Bang nucleosynthesis


  1. Formation of hydrogen and helium nuclei

  2. Hydrogen and helium nuclei attract electrons to form neutral atoms, about 300,000 years after the Big Bang

  3. Ratio of 75% hydrogen and 25% helium formed
• The ratio of hydrogen to helium formed in the Big Bang is still seen in the universe today
• Stellar nucleosynthesis


  Formation of elements heavier than helium through fusion in the cores of stars
• Stellar nucleosynthesis


  1. Young stars use hydrogen and helium to fuel fusion

  2. Fusion of smaller nuclei into heavier elements as the star's core collapses and temperature/pressure increases

  3. Fusion can create elements up to iron
• Supernova nucleosynthesis


  Formation of elements heavier than iron during supernova explosions
• Supernova nucleosynthesis


  1. Supernova explosions have extremely high temperatures (100 billion degrees Celsius) and abundant neutrons

  2. These conditions allow for the creation of elements heavier than iron
• All elements heavier than iron are formed through supernova nucleosynthesis