🪐intro to astronomy review

Open cluster

Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025

Definition

Open clusters are groups of stars that formed from the same molecular cloud and are loosely bound by mutual gravitational attraction. They typically contain a few hundred to a few thousand stars and are found primarily in the galactic plane.

5 Must Know Facts For Your Next Test

  1. Open clusters often contain young stars, with ages ranging from a few million to several billion years.
  2. They are crucial for studying stellar evolution because their star members have similar ages and compositions.
  3. The Pleiades is one of the most famous examples of an open cluster.
  4. Open clusters tend to disperse over time due to interactions with other stars and molecular clouds.
  5. They are important tracers of spiral arm structure in galaxies since they form within these regions.

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