Mysterious "two-faced" star explained, scientists say

Scientists looking at X-rays from a binary star system in the M15 globular star cluster have long been puzzled by the star system, which seemed to have two different sets of characteristics. Now, using the powerful Chandra X-ray Observatory to observe the star system, they've solved the puzzle. What had been thought of as one star system is really two. Previous observations had always been unable to distinguish them. The broader implication of the Chandra discovery is that these types of binary star systems (a neutron star orbiting another star) can be quite common in star clusters, as was theorized but never observed.