A Black Hole Accreting Matter from a Companion Star (image) NASA/Goddard Space Flight Center Share Print E-Mail Caption The nature of ultraluminous X-ray sources remains controversial, but many astronomers think that some or most of these objects consist of an intermediate-mass black hole that accretes matter from a companion star. Recent evidence suggests that a ULX in the galaxy NGC 5408 has a black hole with about 2,000 solar masses. Credit NASA Usage Restrictions None Share Print E-Mail 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.