Free Astronomy Magazine July-August 2021

JULY-AUGUST 2021 the first measurement of the extent of a collection of black holes in a core-collapsed globular cluster. Globular clusters are extremely dense stellar systems, in which stars are packed closely together. They are also typically very old — the globular cluster that is the focus of Hubble uncovers concentration of small black holes S cientists were expecting to find an intermediate-mass black hole at the heart of the globu- lar cluster NGC 6397, but instead they found evidence of a concentra- tion of smaller black holes lurking there. New data from the NASA/ESA Hubble Space Telescope have led to by NASA/ESA - Bethany Downer T his ancient stellar jewelry box, a globular cluster called NGC 6397, glitters with the light from hundreds of thousands of stars. [NASA, ESA, and T. Brown and S. Casertano (STScI). Ack: NASA, ESA, and J. Anderson (STScI)]