Chinese Astronomers Discovered The Most Lithium-Rich Giant Star

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Chinese astronomers have discovered the most lithium-rich giant star ever known, which could shed new light on the evolution of the universe.

With 3,000 times more lithium than a normal star, it was found in the direction of Ophiuchus, on the north side of the galactic disk, at a distance of 4,500 light years from Earth and the star has a mass almost 1.5 times our sun reported by the researchers at National Astronomical Observatories of China (NAOC) and Chinese Academy of Sciences.

The discovery was made with the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST), a special quasi-meridian reflecting Schmidt telescope located in NAOC’s Xinglong Observatory, in Hebei province. The telescope can observe about 4,000 celestial bodies at one time and has made a massive contribution to the study of the structure of the galaxy.

Together with hydrogen and helium, Lithium is considered one of the three elements synthesized in the Big Bang. The abundance of the three elements was regarded as the strongest evidence of the Big Bang, which describes how the universe expanded from a very high-density and high-temperature state. The metal is widely used in electronics. Lithium batteries power mobile phones, laptops, electronic vehicles and drones.

The evolution of lithium has been a key subject in the research of the evolution of the universe and stars. However, giant stars rich in lithium are very rare, with only a few found over the past three decades. Professor ZHAO Gang said, “The discovery of this star has largely increased the upper limit of the observed lithium abundance, and provides a potential explanation to the extremely lithium-rich case.

Detailed information of the star was obtained by a follow-up observation from the Automated Planet Finder (APF) telescope at Lick Observatory. Besides measuring the anomalously high lithium abundance, the research team also proposed a possible explanation for the lithium-rich phenomenon by the nuclear network simulation with the up-to-date atomic data as an input. Lithium-rich stars were first discovered by American astronomers George Wallerstein and Chris Sneden in 1982.

The research team was surprised to find the star had such a large amount of lithium in relation to its age. Giant stars generally contain only small amounts of lithium. One hypothesis was that the star swallowed its planet, like the sun consuming the Earth and absorbed its lithium.