Scientists have traced the mystery behind the high abundance of Lithium in some evolved stars for the first time.
Batteries have powered our planet for the past century. From the smallest technology to huge machines, batteries have played a pivotal role in expanding the horizons of humankind. In a recent breakthrough, scientists have found a clue to the mystery behind the high abundance of Lithium in some evolved stars. Lithium is a trace element on Earth and is a key component of rechargeable batteries.
Lithium-rich stars are burning helium in their core
Astronomers have known for the past four decades that a class of stars hold an anomalous amount of Lithium on their surface. The reason and processes behind the high abundance of Lithium in about one percent red giants has remained a puzzle since the models of how stars evolve predict the Lithium must have been destroyed in the hot plasma of the star.
A team of two scientists has confirmed for the first time that all the lithium-rich stars are burning helium in their core. Deepak from the Indian Institute of Astrophysics (IIA) Bangalore (an autonomous institute of the Department of Science & Technology, DST) and Professor Emeritus David L. Lambert from the University of Texas at Austin and an Honorary Fellow of IIA Bangalore have speculated in their paper published in the journal MNRAS (Monthly Notices of the Royal Astronomical Society) that lithium production is linked to the violent helium-core flash.
Deepak elaborated on the mystery of high abundance of lithium and said “About four decades ago, a red giant with extraordinarily high lithium abundance at its surface was discovered. In all other respects, this red giant was of normal composition. Early follow-up investigation of lithium among red giants showed that just about one percent of sun-like red giants had a lithium-enriched surface. The questions on processes that led to a 100-fold or so increase in the lithium abundance in this exceptional red giant and the reason behind this selective enrichment of lithium in the one percent of red giants intrigued us.”
How the Study commenced
To start the study, the authors drew on a large survey of the compositions of red giants undertaken in Australia at the Australian National University with observations gathered on the 3.9 m Anglo-Australian Telescope at the Australian Astrophysical Observatory. The survey GALAH provided a collection of about 500,000 stars with well-determined physical and chemical properties, including lithium abundances.
The team separated GALAH's stars into several mass and metallicity ranges and then searched for lithium-rich giants among these groups. This study is conducted for the first time on such a large scale and across a wide range of mass and metallicity, which reveals the rare presence of lithium-rich giants in all the Sun-like low-mass stars.
They created virtual stars of various masses and metallicity and compared the properties of these virtual stars with that of real stars from the GALAH survey. These comparisons confirmed that all the lithium-rich stars are burning helium in their core.
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