Instead of circling around a normal star, the low-mass object—likely the "skeleton" of a smaller star—orbits a rapidly spinning pulsar, or neutron star.
The neutron star spins hundreds of times a second—faster than a kitchen blender.
The odd mass, which was spotted on June 7 by NASA's Swift and Rossi X-ray Timing Explorer (RXTE) satellites, orbits the bigger star in a little under once an hour.
The body is located about 230,000 miles (370,149 kilometers) away from the star—slightly less than the distance from Earth to the moon.
Neutron stars usually slow with age, but the gas spiraling from the bizarre object has likely maintained, or even increased, the star's speed.
The star siphons off gas from the orbiting body, as seen in the above artist's illustration. The gas flow occasionally becomes unstable and causes the bright outbursts that can be seen from Earth.
Astronomers suspect the system was once two stars, which formed billions of years ago. Eventually the larger star went supernova, leaving behind the neutron star, while the smaller star expanded into a red giant.
It's unknown whether the smaller star will survive much longer, however.
"It's been taking a beating," Hans Krimm of NASA's Goddard Space Flight Center said in a statement. The neutron star, after all, has been siphoning away its mass for billions of years.
Source : National Geographic