X-ray binaries are discovered through space telescopes, which focus on very short-wave energy radiation sources. The International Explorer and the Einstein X-Ray Observatory and other satellites have been used. Some semi-detached pairs emit x–rays provided by mass transfer in a common atmospheric envelope. Close pairs with one component, a neutron star or a black hole, are likely indicated from enormous energy output in the form of ultraviolet and x-rays which are generated around the massive star as gas from the companion, unevolved star, is sucked toward the massive central degenerate component. This type of binary may have a period of revolution around two days or less.
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Sarah Lee Lippincott
Science EncyclopediaScience & Philosophy: Bilateral symmetry to Boolean algebraBinary Star - Importance, Visual Binaries, Study Of Orbital Motion, Astrometric Binaries, Spectroscopic Binaries, Eclipsing Binaries - Techniques of observation