GRS 1915 (IMAGE) Chandra X-ray Center Caption Researchers monitored this system with Chandra and RXTE for over eight hours and saw that it pulses in X-ray light every 50 seconds. This type of rhythmic cycle resembles an electrocardiogram of a human heart, though at a slower pace. The inset to the upper left shows a Chandra image of the system, while the one to the lower right contains its "heartbeats." The main graphic shows the crowded field containing GRS 1915 in optical light. Credit X-ray: NASA/CXC/Harvard/J. Neilsen et al.; Optical: Palomar DSS2 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.