Stellar cluster
From Memory Alpha, the free Star Trek reference
Stellar clusters are groups of stars that are held together by gravitational forces. Stellar clusters, or star clusters, may be compact groups of hundreds of thousands older stars, or smaller, more open clusters of only a few hundred younger stars. Because stars in a cluster were all born at about the same time, the stars in a cluster differ only in their mass. Many theories of stellar evolution theories rely on observations of stellar clusters to prove hypothesis.
The Federation established a colony in the Strnad system inside a stellar cluster of over 3,000 stars in 2364. (TNG: "Justice")
The Dorias Cluster contains over twenty star systems including several inhabited planets. (TNG: "Bloodlines")
The Muratas Star Cluster in the Delphic Expanse is home to the planet Triannon. (ENT: "Chosen Realm")
The Think Tank at one point claimed to have re-ignited the red giants of the Zai Cluster. (VOY: "Think Tank")
