Stars in a star cluster can change by either becoming runaway stars and escaping through high velocity, or when failing to reach the necessary speeds, they become a permanent part of the cluster. The larger and older stars also eventually become red giants, according to the University of Oregon.Continue Reading
Stars are formed from large clouds of molecular gas, which are made up of many hundreds of solar masses of material. A "solar mass" is a unit of measurement that is equal to the mass of the sun. The gas that remains is heated and then blows away, leaving stars to accumulate in clusters through gravitational pull.
Once part of a cluster, individual stars can take one of two courses over time. They can be forced out of the cluster by reaching escape velocity, or they can remain a part of the cluster, through gradually drifting away from the center, according to NASA.
The stars that are farthest away from the center of the cluster are the oldest, and become red giants over time as the star loses hydrogen fuel in its core. As the star begins to collapse, it causes the outer shell to heat to fusion point, according to the University of Oregon. Over time, rock formation can begin, as the stars continue to heat and compress, allowing the stars to form new mass. Learn more about Astronomy