NASA satellite shows black hole 'bulls-eye' eruption
NASA said its Swift satellite has imaged some of "the best dust-scattered X-ray ring images ever seen" from a black hole outburst. The V404 Cygni black hole and its companion star, about 8,000 light years away, are known to eject high-energy particles every 20 years or so. Swift's X-ray telescope detected the start of a new burst on June 15th, grabbing the attention of scientists at the University of Leicester, UK. On June 30th, they captured an eruption of concentric rings from the system that covered a portion of the sky about half the diameter of the moon.
The rings are actually multiple layers of interstellar dust between 4,000 and 7,000 light years away. Some X-rays from the black hole burst hit Swift's X-ray detectors directly, while others reflected off the dust, delaying their arrival slightly. That makes the rings appear to "echo" into space, the same way that sound reverberates in a canyon. The echoing is useful to scientists, helping them see the rings evolve over time. "With these observations, we can make a detailed study of the normally invisible interstellar dust in the direction of this black hole," said lead researcher Andrew Beardmore.
The researchers aren't totally sure why V404 Cygni's X-ray bursts happen so sporadically, but they do have a theory. The black hole's companion star orbits it every 6.5 days at a close distance, meaning it's likely distorted into an egg shape by the gravity. Material ejected by the star accumulates around the black hole until it reaches critical mass. At that point, "thermonuclear runaway" fusion rapidly burns up the material, creating a bright X-ray flash. Suffice it to say, that's just one reason you wouldn't want to live on a planet in that star's system, as Interstellar showed,
