Deep-sky object class

Stellar Association

A loose grouping of young, massive stars that formed together but are not gravitationally bound, so they drift apart over tens of millions of years. OB associations trace the sites of recent star formation along a galaxy's spiral arms and are often still embedded in the gas of their parent clouds.

Highlights

›Unbound young stars drifting from their birthplace

Open Cluster
Star-Forming Regions
Molecular Clouds

Across the encyclopedia

Open Cluster

Knowledge connections

Associated withOpen Cluster
Associated withOpen Cluster
Associated withStar-Forming Regions
Associated withMolecular Clouds

Sources

The primary and reference sources this topic draws on.

NASANational Aeronautics and Space Administration
Mission data, planetary science, space telescopes, and public-domain imagery.
Most NASA-produced imagery is in the public domain; individual items are checked for usage terms before publication.