HD 140283

An ancient star, HD 140283 is at least 13.2 billion years old and was likely formed shortly after the Big Bang.

The object consists almost entirely of hydrogen and helium, a hallmark of having formed early in the history of the universe, before successive generations of stars had a chance to forge heavier elements. The chemical composition of HD 140283 - a low but nonzero abundance of heavy elements - shows that the star must have formed after the first stellar generation.

HD 140283 has advanced to a phase in which it is exhausting the hydrogen at its core. In that phase, the star's slowly dimming luminosity is a highly sensitive indicator of its age.