Neutron star is caught blowing bubbles

时间:2019-03-08 04:13:19166网络整理admin

By Jeff Hecht in Boston EXOTIC bubbles of radiation on the boiling polar caps of a neutron star are firing off giant blasts of energy in as little as half a millisecond, satellite observations have revealed. Neutron stars form when the core of a massive star collapses, squeezing matter into a ball of neutrons about 20 kilometres across, sometimes with a strong magnetic field. If it has a normal companion star, a neutron star can pull gas from the companion into a disc around itself. Matter from this disc heats to millions of degrees and emits X-rays as it falls onto the neutron star’s magnetic poles. A decade ago, Richard Klein of the Lawrence Livermore National Laboratory in California predicted that the intense X-rays emerging from the surface could become trapped in the infalling matter. The energetic froth would then form “photon bubbles”, which would rise a kilometre or two above the surface before popping to release the trapped X-rays. Three years ago, astronomers spotted similar bursts coming from a weakly magnetised neutron star (New Scientist, Science, 11 May 1996, p 18). Now Klein and his colleagues Garrett Jernigan and Jonathan Arons of the University of California at Berkeley have seen much more energetic X-ray bubbles in action. Using data from NASA’s Rossi X-ray Timing Explorer satellite, they have shown that the X-ray bubbles grow and burst in 0.5 to 10 milliseconds on a strongly magnetised neutron star called Centaurus X-3, about 30 000 light years from Earth. At a meeting of the American Astronomical Society in Charleston, South Carolina, last week the researchers said the X-rays bubble up from polar regions that make up just 3 per cent of the surface of the neutron star. “The energy released is of the order of several billion nuclear bombs per second per square metre,