The above image is of a globular cluster named 47 Tucanae. A typical globular cluster is 20 parsecs or more in diameter. The stars within a globular cluster are more closely packed than in an open cluster. There are about 200 globular clusters associated with our galaxy. Globular clusters, unlike open clusters, are NOT confined to the central plane of our galaxy.
Globular clusters contain no dust, no gas, and no massive main sequence stars.
Laboratories are generally thought of as places where scientists can run controlled experiments to test their hypotheses and theories. Unfortunately, astronomers cannot create stars in their home workshops. However, the galaxy has helped us out to some extent by creating stars in clusters, instead of creating them one by one in random places, at random times, under wildly varying conditions of temperature, density, and chemical composition. Stars in a cluster formed at the same time, in the same molecular cloud. Therefore, stars in a cluster have the same age, had the same initial chemical composition, and are at roughly the same distance from Earth.