Astronomers Have Discovered Rare Binary Star System

According to new study astronomers have discovered a rare binary star system by following its powerful gamma-ray signal, a find that may remove the element of luck from locating more its kind. Unlike other gamma-ray twin star systems found by chance, a direct search for gamma rays revealed the newfound binary system 1FGL J1018.6-5856 about 15,000 light-years away. The method may be a new tool to identify more of these hard-to-find stellar pairs. High-energy gamma rays are challenging to locate because so few of the photons streaming from the system make it to Earth. An international collaboration of astronomers used the Large Area Telescope on NASA’s Fermi Gamma-ray Space Telescope. Launched in 2008, the telescope sweeps the sky over several hours, making it ideal to search for objects whose gamma-ray brightness varies regularly. Gamma-ray binary star systems come in two flavors, and identifying which an object presents is its own challenge. Some are born of microquasars, neutron stars or black holes the size of the sun pilfering material from a massive companion star, with fast jets shooting from the top and bottom. The system 1FGL J1018.6-5856, however, is thought to be a special pulsating type of neutron star, interacting with the stellar wind of its companion. The two circle one another about every 17 days. Gamma-ray binaries are a rare breed. Only four others are known. But astronomers believe the systems that contain a quick-spinning pulsar eventually become relativelqy slow-spinning X-ray binary stars, which are far more plentiful. Astronomers hopes that an ongoing, consistent search with Fermi will turn up other gamma-ray binaries that have gone undetected, leading to a greater understanding of how they evolved.
source:www.space.com