An eclipsing binary star is a binary star in which the orbit plane of the two stars lies so nearly in the line of sight of the observer that the components undergo mutual eclipses. In the case where the binary is also a spectroscopic binary and the parallax of the system is known, the binary is quite valuable for stellar analysis. Image File history File links Eclipsing_binary_star_animation_2. ... A binary star system consists of two stars both orbiting around their barycenter. ... In physics, an orbit is the path that an object makes, around another object, whilst under the influence of a source of centripetal force, such as gravity. ... The Pleiades star cluster A star is a massive body of plasma in outer space that is currently producing or has produced energy through nuclear fusion. ... Photo taken during the French 1999 eclipse An eclipse (Greek verb: ecleipo, to cease existing or calypse, to cover ) is an astronomical event that occurs when one celestial object moves into the shadow of another. ... A spectroscopic binary star is a binary star which cannot be resolved as a visual binary, even with telescopes of the highest existing resolving power. ... Parallax (Greek: παραλλαγή (parallagé) = alteration) is the change of angular position of two stationary points relative to each other as seen by an observer, due to the motion of an observer. ...

Eclipsing binaries are variable stars, not because the light of the individual components vary but because of the eclipses. The most notable eclipsing binary is the star Algol (β Persei), named the "demon star" by the Arabs in all probability because they noticed the variation in its light. Most stars are of nearly constant luminosity. ... ALGOL (short for ALGOrithmic Language) is a family of imperative computer programming languages originally developed in the mid 1950s which became the de facto standard way to report algorithms in print for almost the next 30 years. ... Perseus is a northern constellation, named after the Greek hero who slew the monster Medusa. ... The Arabs (Arabic: عرب Ê»arab) are a large and heterogeneous ethnic group found throughout the Middle East and North Africa, originating in the Arabian Peninsula of southwest Asia. ...

The light curve of an eclipsing binary is characterized by periods of practically constant light, with periodic drops in intensity. If one of the stars is larger than the other, one will be obscured by a total eclipse while the other will be obscured by an annular eclipse. In astronomy, a light curve is a graph of light intensity as a function of time. ...

The period of the orbit of an eclipsing binary may be determined from a study of the light curve, and the relative sizes of the individual stars can be determined in terms of the radius of the orbit by observing how quickly the brightness changes as the disc of the near star slides over the disc of the distant star. If it is also a spectroscopic binary the orbital elements can also be determined, and the mass of the stars can be determined relatively easily, which means that the relative densities of the stars can be determined in this case. In physics, an orbit is the path that an object makes, around another object, whilst under the influence of a source of centripetal force, such as gravity. ... The elements of an orbit are the parameters needed to specify that orbit uniquely, given a model of two ideal masses obeying the Newtonian laws of motion and the inverse-square law of gravitational attraction. ...