OSAKA: A large amount of lithium, one of the key elements in the chemical evolution of the cosmos, is produced by stellar explosions called novae.
The findings, reported in the journal Nature, provide the first direct evidence that lithium, which is used for lithium-ion batteries in computers, smart phones and eco-cars, is produced by stellar objects.
“Understanding the way lithium is produced, means we can now understand every process of elemental production in the universe,” says the study’s lead author Dr Akito Tajitsu of the National Astronomical Observatory of Japan.
A nova is an extremely bright thermonuclear explosion on the surface of a white dwarf, the slowly cooling core of a star like our Sun after its run out of hydrogen and helium fuel.
Because white dwarfs have long lives and can experience multiple nova events, it means the total production of lithium will be quite large over the history of the universe, says Tajitsu.
The origin of lithium and its production process have long been uncertain.
Together with hydrogen and helium, a small amount of lithium was generated directly through Big Bang nucleosynthesis and is now produced through collisions between cosmic ray particles and gas in the interstellar medium.
Chemical evolution models and observed lithium abundances in the Milky Way indicate at least half of all the lithium is produced in old bloated stars called red giants, in their successors known as asymptotic giant branch stars, and by novae.
But lithium is very fragile at the high temperatures found in stars, and so until now there’s been little direct evidence to support the idea of novae being a major source of lithium.
