Starstruck in Terzan 4

A glittering multitude of stars in the globular cluster Terzan 4 fill this image from the Hubble Space Telescope. Globular clusters are collections of stars bound together by their mutual gravitational attraction, and can contain millions of individual stars. As this image shows, the heart of a globular cluster such as Terzan 4 is a densely packed, crowded field of stars. The launch of Hubble in 1990 revolutionized the study of globular clusters. The individual stars in these dense crowds are almost impossible to distinguish from one another with ground-based telescopes, but can be picked apart using space telescopes. Astronomers have taken advantage of Hubble’s crystal-clear vision to study the stars making up globular clusters, as well as how these systems change over time. This particular observation comes from astronomers using Hubble to explore Terzan 4 and other globular clusters to understand the shape, density, age, and structure of globular clusters close to the center of the Milky Way.