HE 1523-0901
The star's age, as measured by ESO's Very Large Telescope, is 13.2 billion years. This makes it among the oldest stars and nearly as old as the estimated age of the universe itself (13.8 billion years as measured by Planck). The measurement uncertainty in the age estimate is 0.7 to 2.7 billion years, depending upon the assumptions made to estimate the uncertainty, although the uncertainty in the relative age of this and other stars using the same method is smaller. HE 1523-0901 is the first star whose age was determined using the decay of the radioactive elements uranium and thorium in tandem with measurements of several neutron capture elements. It is believed to have formed directly from the remnants of the first-generation stars that reached the end of their longevity and exploded as supernovae early in the history of known matter.