NASA's Fermi Gamma-ray Space Telescope has made the first unambiguous detection of high-energy gamma-rays from an enigmatic binary system known as Cygnus X-3.

The system pairs a hot, massive star with a compact object - either a neutron star or a black hole - that blasts twin radio-emitting jets of matter into space at more than half the speed of light.

"Cygnus X-3 is a genuine microquasar and it's the first for which we can prove high-energy gamma-ray emission," said Stéphane Corbel at Paris Diderot University in France.

The system, first detected in 1966 as among the sky's strongest X-ray sources, was also one of the earliest claimed gamma-ray sources. Efforts to confirm those observations helped spur the development of improved gamma-ray detectors, a legacy culminating in the Large Area Telescope (LAT) aboard Fermi.

At the center of Cygnus X-3 lies a massive Wolf-Rayet star. With a surface temperature of 180,000 degrees F, or about 17 times hotter than the sun, the star is so hot that its mass bleeds into space in the form of a powerful outflow called a stellar wind. "In just 100,000 years, this fast, dense wind removes as much mass from the Wolf-Rayet star as our sun contains," said Robin Corbet at the University of Maryland, Baltimore County.

Every 4.8 hours, a compact companion embedded in a disk of hot gas wheels around the star. "This object is most likely a black hole, but we can't yet rule out a neutron star," Corbet noted.

"In Cygnus X-3, an accretion disk surrounding a black hole or neutron star orbits close to a hot, massive star. Gamma rays (purple, in this illustration) likely arise when fast-moving electrons above and below the disk collide with the star's ultraviolet light. Fermi sees more of this emission when the disk is on the far side of its orbit. (Credit: NASA's Goddard Space Flight Center)"

Source: NASA