By Ron Cowen
Using particle accelerators to mimic the conditions inside stars, two independent research groups have found evidence that the most-ancient known stars are about a billion years older than astronomers had estimated. This provides new evidence that the universe is about 14 billion years old.
The age recalibration rests on a nuclear reaction that prevails in old stars that have nearly exhausted the hydrogen at their cores. For most of its life, a star produces energy by fusing hydrogen nuclei to make helium. The fusion occurs at a leisurely rate, but when little hydrogen is left, the star activates an alternative helium-making process, which is based on collisions between protons and nuclei of carbon, nitrogen, and oxygen.