Complex sentence: In 2007 a cluster of approximately 50,000 newly formed stars named RSGC2 was located only a few hundred light years from RSGC1; it is thought to be less than 20 million years old and contains 26 red supergiant stars, the largest grouping of such stars known.
Split into simpler sentences: In 2007 a cluster of approximately 50,000 newly formed stars named RSGC2 was located only a few hundred light years from RSGC1. It is thought to be less than 20 million years old and contains 26 red supergiant stars, the largest grouping of such stars known.