Giant ring of black holes in Arp 147

    Arp 147 contains a spiral galaxy (right) that collided with an elliptical galaxy (left), triggering a wave of star formation. Many of these newly-born massive stars raced through their lives and ended with supernova explosions, some as black holes. A ring of these black holes can be seen in the Chandra data (pink) around the spiral galaxy. Chandra X-ray Observatory