Until now, astronomers had suspected that globular clusters like the one pictured here (Omega Centauri) were the most likely place to find medium-sized black holes -- elusive objects that have proved difficult to pin down. The latest study analyzed a globular cluster called RZ2109 and found it does not possess a medium-sized black hole. RZ2109 is much farther away from Earth than Omega Centauri. Credit: NASA/JPL-Caltech/NOAO/AURA/NSF
