The star cluster gains gravity and forms a large spherical heap of stars with enormous gravity. This is a globular cluster. It pulls gas and other matter such as asteroids into the churning disk. Open clusters will not form a large mass but instead will eventually drift apart. There is a continuous pattern related with stars and nebulae.
Stars explode and the dust forms a nebula.
The nebula gives birth to stars. Those stars once again explode and the dust adds to the nebula. It is all a cycle of birth, death, and recycling.