Globular star clusters are isolated star cities, home to hundreds of thousands of stars. And like the fast pace of cities, there's plenty of action in these stellar metropolises. The stars are in constant motion, orbiting around the cluster's center. Past observations have shown that the heavyweight stars live in the crowded downtown, or core, and lightweight stars reside in the less populated suburbs.
But as heavyweight stars age, they rapidly lose mass, cool down, and shut off their nuclear furnaces. After the purge, only the stars' bright, super-hot cores remain, and they are called white... Read more