Astronomy & Space Science · AST-552
Galaxy Groups & Clusters: Structures & Vocabulary
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Structure
Structure of Galaxy Groups & Clusters
A cluster includes member galaxies, diffuse intracluster plasma, dark matter, and often a massive central galaxy. Groups are less massive and have lower velocity dispersions, making galaxy mergers relatively easier.
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References & evidence
Source library for this chapter
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- 01The Evolution and Distribution of Galaxies — SummaryOpen source ↗
OpenStax Astronomy 2e
View claim-by-claim traceability3 verified claims
Galaxies are strongly clustered rather than randomly distributed.
supported · checked Sep 22, 2026Clusters grow through gravitational collapse and hierarchical merging of smaller halos.
supported · checked Sep 22, 2026Galaxy redshifts and velocities reveal bound populations, X-ray emission maps hot gas, gravitational lensing maps total mass, and the motions of galaxies require far more mass than visible stars alone provide.
supported · checked Sep 22, 2026