Circinus X-1 (IMAGE) University of Wisconsin-Madison Caption Circinus X-1 is a bizarre and sometimes frenetic source of X-rays in our galaxy. Residing in the plane of the Milky Way, where it cannot be observed by optical telescopes because of obscuring clouds of interstellar dust, Circinus X-1 is the glowing husk of a binary star system that exploded in a supernova event just 2,500 years ago. It consists of a very dense neutron star locked in the orbital embrace of a companion star. The system is called an X-ray binary because it flashes in X-rays as material from the companion star is sucked onto the dense neutron star. Credit NASA/Chandra X-ray Observatory Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.