What is Big Bang Nucleosynthesis (BBN)?


Recently Indian researchers have discovered hundreds of Li-rich giant stars produced during BBN indicating that Li is being produced in the stars and accounts for its abundance in the interstellar medium.

About Big Bang Nucleosynthesis (BBN)

  • BBN is the production of nuclei other than those of the lightest isotope of hydrogen during the early phases of the Universe.
  • Primordial nucleosynthesis is believed by most cosmologists to have taken place in the interval from roughly 10 seconds to 20 minutes after the Big Bang.
  • It is calculated to be responsible for the formation of most of the universe’s helium in various isotopic forms.
  • Essentially all of the elements that are heavier than lithium were created much later, by stellar nucleosynthesis in evolving and exploding stars.

Lithium in space

  • Lithium (Li), is one of the three primordial elements, apart from Hydrogen and Helium (He), produced in the Big Bang Nucleosynthesis (BBN).
  • However, the present measurement of Li in the interstellar medium and very young stars is about 4 times more than the primordial value.
  • Thus, identifying sources of Li enrichment in our Galaxy has been a great interest to researchers to validate BBN as well as a stellar mixing process.
  • In general, stars are considered as Li sinks. This means that the original Li, with which stars are born, only gets depleted over stars’ life-time as Li burns at relatively very low temperatures.

Source: PIB