Single exposure image of M92, globular cluster in Hercules. Nikon D40, 14 inch LX200 ACF. Globular clusters are made of old stars. Their is no associated nebulosity as it has nearly all been used to form the stars in the cluster. Ols stars like this are called, "metal rich." Although their are atoms of metal elements in these stars (and metals accumulate as stars age), the term is misleading. In astrophysics, anything that is not hydrogen or helium is classed as a metal.