14 DAY TRIAL // Though astronomers know that as much as one fifth of all stars in the Milky Way may exist in binary systems, they are still having a hard time finding the more obscure pairs. In a recent study, a fortuitous discovery may have just highlighted a new method of searching for such hidden stellar pairs.
A binary is a system made of two stars. They may orbit each other, a smaller one may orbit around a larger one, or the two may orbit around a common center of gravity. Depending on their size and distance from Earth, they can indeed be difficult to observe.
In a recent investigation, scientists were able to discover a new binary system – which they unimaginatively dubbed 1FGL J1018.6-5856 – some 15,000 light-years from Earth. The interesting thing is that they did so by following the stars' gamma-ray signature.
Gamma-rays are the most energetic forms of light in the Universe, with energy levels exceeding those of visible light billions of times over. They most often travel in bursts, which are produced by such things as neutron star mergers, black holes' event horizons, exploding supernovae and so on.
What researchers did not know was that following a stream of gamma-rays to its origins may reveal binary systems. The new discovery highlights a new potential use for telescopes operating at these wavelengths, such as NASA's Fermi, which is to search for obscure binary systems.
“Even if the system is giving out as much energy in gamma rays as in optical light, we still don't get many photons coming in the gamma-ray regime,” due to the great distance between 1FGL J1018.6-5856 and Earth, explains Robin Corbet.
The expert holds an appointment as the XTE SOF Chief Duty scientist/manager at the NASA Goddard Space Flight Center (GSFC) Laboratory for High Energy Astrophysics. He explains that only very few high-energy photons make their way to Earth daily, and even fewer are detected once they get here.
“We’re really hoping that this is the tip of the iceberg. We've got our fingers crossed that as Fermi continues its mission for more years and our measurements get more and more sensitive, we'll find even more binaries,” says the investigator, quoted by Space.
In addition to mapping high-energy sources throughout the night sky, the Fermi Gamma-Ray Telescope is now also being used to monitor the Universe for any telltale signs of hidden binary star systems.