Globular clusters like NGC 6558 are tightly bound collections of tens of thousands to millions of stars, and they can be found in a wide range of galaxies. As this observation shows, the stars in globular clusters can be densely packed; this image is thronged with stars in a rich variety of hues. Some of the brightest inhabitants of this globular cluster are surrounded by prominent diffraction spikes, which are imaging artefacts caused by starlight interacting with the inner workings of Hubble.
Globular clusters equip astronomers with interesting
natural laboratories in which to test their theories, as all the stars
in a globular cluster formed at approximately the same time with similar
initial composition. These stellar clusters therefore provide unique
insights into how different stars evolve under similar conditions. This
image comes from a set of observations investigating globular clusters
in the inner Milky Way. Astronomers were interested in studying these
globular clusters to gain greater insight into how globular clusters in
the inner Milky Way form and evolve.
