Astronomers locate oldest known star in Milky Way

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The Independent Online

Astronomers may have detected the oldest star in the Milky Way galaxy, which could date back to the beginning of the Universe more than 12 billion years ago.

Astronomers may have detected the oldest star in the Milky Way galaxy, which could date back to the beginning of the Universe more than 12 billion years ago.

The star lies towards the southern constellation of Phoenix, about 36,000 light years from Earth. It is among the 10,000 or so brightest stars in the sky. An analysis of its chemical composition suggests that the star, known only by its catalogue name, HE0107-5240, is almost devoid of metals. This indicates that it is a relic from the very early history of the galaxy, when it was formed after the Big Bang.

After decades of searching for such a candidate, a team led by Norbert Christlieb at the University of Hamburg in Germany found the star with the help of observations using the Anglo-Australian telescope in New South Wales and the European Southern Observatory in Chile.

Stars are the nuclear cauldrons in which the lighter elements of the Periodic Table, such as hydrogen and helium, are gradually converted into the heavier atoms that are essential for life. For many years astronomers have theorised about the existence of so-called "population III" stars, which contain minimal amounts of heavier atoms, such as iron, and which therefore date back to this much earlier age.

Catherine Pilachowski, an astronomer at Indiana University, said: "These stars would be relics from early in galactic history, before star formation and evolution polluted the primordial gas with metals."

HE0107-5240 has a metallic composition far lower than anything seen before – a metallic concentration that is about one two-hundred-thousandth that of our own star, the Sun. This is about 20 times lower than previous measurements.

Dr Pilachowski said that the results of the study, published in the journal Nature, suggest that the birth of the star could date back to about 1 billion years after the Big Bang.

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