The Beating Gamma-ray Heart of a Microquasar : Big Pic

A microquasar is composed of two objects: a massive star and a massive compact object, like a black hole. As the pair orbit one another, the powerful gravitational field of the black hole steals gas from its companion star. As the black hole sucks over the material, a disk forms around its center, like water circling a drain, and jets of hot matter blast from the poles. Those powerful jets generate a radio signal that's easy to identify.

NASA's Fermi Gamma-ray Space Telescope has spotted gamma-rays coming from the microquasar Cygnus X-3, which is 37,000 light-years away, in the constellation Cygnus. Scientists already know that Cygnus X-3 generates a broad range of powerful radiation, but this is the first time they've seen gamma-ray radiation from a microquasar.

Cygnus X-3 is what's called a binary system -- with two stellar objects orbiting each other -- composed of a massive, old O-class star in the final, violent stages of its life (a so-called Wolf-Rayet) orbiting a black hole or a neutron star.

The pair orbits each other every 4.8 hours and the hot Wolf-Rayet is losing huge amounts of gas to its greedy friend's accretion disk.

It's thought the gamma-ray radiation in Cygnus X-3 is generated as the Wolf-Rayet's intense ultraviolet light interacts with the whirling electrons in its partner's disk.

Microquasars are named after their larger cousins, quasars, since they share many of the same characteristics. However, quasars are composed of supermassive black holes in the center of active galaxies that consume vast amounts of material (very active quasars can consume the equivalent of 600 Earths per minute). So microquasars are tiny in comparison.

Image: Our galaxy's gamma-ray emission profile as viewed by Fermi's Large Area Telescope (LAT). In the sub-image, Cygnus 3-X is shown (circled) with two brighter gamma-ray sources (pulsars). Credit: NASA/DOE/Fermi LAT Collaboration