NICER Data on Low-Mass Binary (IMAGE) NASA/Goddard Space Flight Center Caption During NICER commissioning, an observation of low-mass X-ray binary 4U 1608-522 revealed a serendipitous Type I X-ray burst, a flare resulting from a thermonuclear explosion on the surface of a neutron star. 4U 1608 consists of a neutron star in a close orbit with a low-mass star from which it is drawing gas. As this matter accretes and piles up on the neutron star surface, its density in the strong-gravity environment increases until an explosive nuclear fusion reaction is ignited. The heated neutron star surface and atmosphere glow in X-rays, cooling and dimming over the span of about one minute. The hot-spot on the star swings in and out of NICER's view as the star spins, approximately 619 times each second; these fluctuations in X-ray brightness, and their evolution during the burst, are indicated by the purple contours in the lower panel. NICER provides a unique such bursts, tracing flame propagation and other phenomena through the burst's temperature and brightness changes over time, with simultaneous fast-timing and spectroscopy capability not previously available. Credit NASA 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.