Open Star Clusters

An open cluster is a group of up to a few thousand stars that were formed from the same cloud of gas and dust, and are still loosely bound (or tied) to each other by gravity.

In contrast, globular clusters are very tightly bound (tied together) by gravity.

Open clusters are found only in spiral and irregular galaxies, in which star formation is taking place.

The clusters are usually less than a few hundred million years old (young children in human terms), and are slowly drifting apart.