Another term for open cluster as they are typically located in the arms of spiral galaxies where there is abundant dust and gas essential for star formation.
An "open" cluster of stars located in the spiral arms or disk of the Galaxy.
a loose cluster of a small number of stars; aka open cluster
This is an alternative name for an open star cluster in our Galaxy. It indicates that the cluster lies within our Galaxy rather than in the halo round our Galaxy, where globular clusters lie.