sci18058a

Left: The ultra-diffuse galaxy NGC 1052-DF is rich in globular clusters, which hold the key to understanding this mysterious object’s origin and mass. Right: A closer look at one of the globular clusters within the galaxy, which are all much brighter than typical, the brightest emitting almost as much light as the brightest within the Milky Way. The spectrum, obtained by Keck Observatory shows the absorption lines used to determine the velocity of this object. Ten clusters were observed, providing the information needed to determine the mass of the galaxy, revealing its lack of dark matter. Image credit: Gemini Observatory/NSF/AURA/Keck/Jen Miller/Joy Pollard