For elderly stars, the fountain of youth may be only a collision away.
Evidence for the rejuvenating power of collisions comes from studying bright, young-looking stars residing in globular clusters, the oldest stellar groupings in the Milky Way. For nearly 50 years, astronomers examining globular clusters have encountered a paradox. Even though massive stars go for the gusto, burning brightly and dying out in just a few million years, several keep on shining in the dense cores of these clusters, which may be as old as 16 billion years.
According to theory, no star heavier than 80 percent of the sun's mass should reside in an ancient globular cluster. Yet, astronomers have found resident bright stars, known as b