Integral reveals exotic and dusty binary systems   This is an artist's impression of a supergiant high-mass X-ray binary system. ESA’s orbiting gamma-ray observatory Integral has revealed a new population of these exotic and dusty binary stars. These binary systems consist of a neutron star orbiting around a supergiant star. It is possible that these systems represent a brief evolutionary period in a binary star’s life. The results also bring to light a gap in our knowledge about how such binary star systems are formed and evolve. Integral discovered what appeared to be 15 supergiant high-mass X-ray binaries (HMXB). The supergiant star is at least 20 times larger than the Sun, contains 30 solar masses, with luminosity one million times greater and a temperature of 20000K. The neutron star was once a massive star itself, but has reached the end of its life and collapsed into a tiny stellar remnant just 15km across. Sylvain Chaty, University of Paris Diderot, and CEA Saclay France, and colleagues have used Integral, along with X-ray satellites and ESO telescopes, to target the fifteen new discoveries and confirm that most are indeed supergiant HMXBs, some of them enshrouded by a cocoon of gas and dust.   This is an artist’s impression of ESA’s orbiting gamma-ray observatory, Integral. Release date: 3 April 2009