The recent findings from the Indian Institute of Astrophysics (IIA) have given us a fresh glimpse into the life cycle of Sun-like stars. The study shows that these stars not only destroy lithium during their lifetime, but also become significant producers of the element during their helium core burning phase. Here, we break down the significance of these findings and what they mean for our understanding of stellar evolution.
Lithium Production in Stars
Through a large-scale systematic investigation, the scientists from the IIA discovered exciting evidence of lithium production in low-mass, Sun-like stars during their core helium-burning phase. This production event can be traced back to the onset of a ‘He-flash’, a violent eruption marking the ignition of helium at the star’s core after the completion of its hydrogen-burning phase.
In about 6-7 billion years, our own Sun will reach this phase and begin producing lithium. This discovery defies previous beliefs that stars only destroy lithium throughout their lifespan; instead, it suggests that there may be some unknown physical process missing from our current understanding of stellar theory.
Revising the Criteria for Lithium-rich Stars
The findings of this study also necessitate a revisit to the criteria that define lithium-rich stars. Until now, a star was considered lithium-rich if its lithium content was more than 1.5 dex. However, the new research proposes a significantly lower threshold (A(Li) > -0.9~dex), which is 250 times below the earlier limit.
The Origin and Increase of Lithium
Most of the existing lithium in the universe originates from the Big Bang, which occurred around 13.7 billion years ago. Over time, the lithium content in the universe has quadrupled – a modest increase when compared to other elements, which have multiplied by approximately a million times.
Until the IIA’s recent study, lithium was considered the exception to the rule that stars contribute massively to the enhancement of heavier elements through mass ejections and stellar explosions.
The Many Uses of Lithium
Beyond its role in the cosmos, lithium has a wealth of applications here on Earth. Being a light, flammable metal, it is a key component in lithium-ion batteries, playing a crucial role in modern communication devices and transportation methods. The metal is also involved in the manufacture of aircraft.
In addition to its industrial uses, lithium carbonate is commonly used in medicine as a treatment for bipolar disorder, where it helps stabilize the mood swings associated with the illness.
These findings from the Indian Institute of Astrophysics are evidence of how our understanding of the universe is continually evolving. This new knowledge about lithium not only challenges established beliefs about stellar behavior but also opens up exciting new avenues for research into stellar evolution.
