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Binary Star

X-ray Binaries

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.



Couteau, Paul. Observing Double Stars. Cambridge, MA: The MIT Press, 1981.

Introduction to Astronomy and Astrophysics. 4th ed. New York: Harcourt Brace, 1997.

Zeilik, M., and J. Gaustad. Astronomy, the Cosmic Perspective. New York: John Wiley, 1990.


Degirmenci, L. "Formation, Structure And Evolution Of Stars." Astronomy And Astrophysics 363, no. 1 (2000): 244-252.

"Determination of the Ages of Close Binary Stars on the Main Sequence" Astrophysics 45, no. 3 (2002) 342-357.

Sincell, M. " Profile: Twin Stars Of Astrophysics Make Room For Two." Science 293, no. 5532 (2001): 1040-1041.


McAlister, H.A., and Wm. I. Hartkopf, eds. Complementary Approaches to Double and Multiple Star Research, IAV Colloquium 135. ASP Conference Series, Vol. 32, 1992. Published by the Astronomical Society of the Pacific.

Sarah Lee Lippincott


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Astrometric photographs

—Photos taken with "telephoto type" telescopes yielding large scale portrayal suitable for accurate measurements of positions of stellar images.

Dark absorption lines

—Part of the stellar spectrum coming from different atomic elements in the atmosphere of the star.

Doppler shift

—The change in frequency or wavelength resulting from the relative motion of the source of radiation and the observer. A motion of approach between the two will result in a compression of the waves as they pass the observer and a rise in "pitch" in the frequency of the wave and a shortening of the relative wavelength called a "blue shift." A relative motion of recession leads to a lowering of the "pitch" and a shift to longer "redder" wavelengths.

Dynamical orbital elements

—Used in equations to describe the true orbital path of a binary star component in the plane of the orbit.

Geometrical orbital elements

—Used in equations to describe the orbital path of a binary star component as seen on the plane of the sky.


—The quantity of matter in the star as exhibited by its gravitational pull on another object. Stellar mass is usually measured in units of the sun's mass.

Additional topics

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