Globular cluster NGC 6397 is a "core collapsed" cluster that contains about 400,000 stars. Its age is estimated to be about 13.6 billion years, which was determined by using, for the first time, the beryllium content of two stars.
Globular cluster NGC 6397 is a "core collapsed" cluster that contains about 400,000 stars. Its age is estimated to be about 13.6 billion years, which was determined by using, for the first time, the beryllium content of two stars.