A "Fossil" Star Found in our Galaxy | fr584's Blog

Astronomers have found one of the oldest stars known to date. The star, HE 1523-0901, is in the Milky Way and is estimated to be 13.2 billion years old. With such an age, it would have formed just 500 million years after the Big Bang and must have formed very early in the life of our very own galaxy.

To measure the age of the star, astronomers used a technique similar to the carbon-14 dating method used to measure the age of archaeological finds here on Earth. In this case, however, they measured the abundance of radioactive isotopes of Uranium and Thorium. Such a feat can only be performed by the largest telescopes. So the astronomers used ESO's VLT (Very Large Telescope) to observe the star for a total of 7.5 hours with an ultraviolet spectrograph - allowing the spectral lines from the radioactive elements to be observed. This is the first time that more than a single cosmic clock has been measured for a star. In all, a total of six measurements were made and the results suggested that HE 1523-0901 was 13.2 billion years old. This is quite an amazing find considering that the Universe is believed to have existed for only 13.7 billion years!