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The Oldest Star In The Universe

Astronomers have found the oldest star ever seen in our own galaxy, a star that dates back a staggering 13.2 billion years, meaning that it formed just 500 million years after the big bang.

The relic star, known as HE 1523-0901, was observed at ultraviolet wavelengths by the European Southern Observatory's Very Large Telescope. It was discovered by Anna Frebel and her team. Analysing the light, they were able to measure the amount of key radioactive (thorium & uranium) elements in the star.

The dating method utilised by Frebel and her team required the measurement of unstable radioactive elements. This is because, the amounts of these elements found in the star depend very much on the time they have been around. As time goes by these elements decay, and by emasuring the abundances now astronomers can get an idea to how old the object is. The one caveat in the method is that there needs to be enough of that elements present for the astronomers on Earth to measure accurately.

Astronomers have been searching for the first generation of stars to come to a better understanding as to how stars formed in the first place. Most of this first generation has long since died out, but this ancient relic is a vital time capsule that will shed light on one of the earliest eras of the Universe.

An Amateur photograph of HE 1523-0901, the oldest star ever discovered
Image: Anthony Ayiomamitis

  1. Astronomers determine the age of stars through the same concept used by archeologist on earth date a sample. The only different is, archeologist measures the carbon elements (carbon-14 dating technique) in their samples while astronomers measures radioactive elements (thorium & uranium) decay by stars.
  2. HE 1523-0901 is the 11th magnitude, 0.8-solar mass red giant ever discovered.
  3. HE 1523-0901 lies 7500 light years away from Earth, in the constellation of Libra.

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