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A binary system is a system of two astronomical bodies which are close enough that their gravitational attraction causes them to orbit each other around a barycenter also see animated examples. More restrictive definitions binarsystem plattforment that this common center of mass is not binarsystem plattforment within the interior of either object, in order to exclude the typical planet— satellite systems and planetary systems.
The most common binary systems are binary stars and binary asteroidbut brown dwarfsplanetsneutron starsblack holes and galaxies can also form binaries. A multiple system is like a binary system but consists of three or more objects such as for trinary stars and trinary asteroids.
In a binary system the brighter object is binarsystem plattforment to as primaryand the other the secondary. They are also classified based on orbit. Wide binaries are objects with orbits that keep them apart from one another.
They evolve separately and have very little effect on each other. Close binaries are close to each other and are able to transfer mass from one another. They can also be classified based on how we observe them.
Visual binaries binarsystem plattforment two stars separated enough that they can be viewed through a telescope or binoculars. Eclipsing binaries are where the objects' orbits are at an angle that when one passes in front of the other it causes an eclipseas seen from Earth. Astrometric binaries are objects that seem to move around nothing as their companion object cannot be identified, it can only binarsystem plattforment inferred.
The companion object may not be bright enough or may be hidden binarsystem plattforment the glare from the primary object. A related classification though not a binary system is Optical binary which refers to objects binarsystem plattforment are so close together in the sky that they appear to be a binary system but are not.
Such objects merely appear to be close together, but lie at different distances from the solar system. When binary minor planets are similar in size, they binarsystem plattforment be called " binary companions " instead of referring to the smaller body as a satellite.
Pluto and its largest moon Charon are sometimes described as a binary system because the barycenter center of mass of the two objects is not inside either of them. A binary star that has an orbital period of less than 30 years implies that the two system components are less binarsystem plattforment about 10 AU apart. Mass transfer occurs at some stage in most close binaries, profoundly affecting the evolution of the binarsystem plattforment stars.
If the two components are in a close binary and do not fill their Roche lobesthe system is considered a detached binary.
In a semidetached binaryone star fills its Roche lobe and mass transfer occurs. In a contact binaryboth stars fill binarsystem plattforment Roche lobes. The evolution of close binaries depends on the initial masses of the two stars and their separation. When the more-massive star evolves into a red giant first and fills its Roche lobe, material will spill through binarsystem plattforment inner Lagrangian point onto its companion, thereby affecting its companion's evolution.
Mass transfer can also alter the separation and orbital period of the binary star. In binarsystem plattforment that are binarsystem plattforment widely separated, material escaping from the Roche lobe of the evolved red giant immerses the system in material, creating a common-envelope binary that contains the core of the red giant binarsystem plattforment white dwarf and the companion star.
Friction causes the two components to approach, and thus the orbital period to shorten. The common envelope is ejected and a cataclysmic variable star is left, wherein the mass transfer from the companion to the white dwarf causes the periodic outbursts seen in novaerecurrent novaedwarf novaeand symbiotic novae.
If one binarsystem plattforment of a close binary is massive enough, it may become a neutron star or black hole instead of a white dwarf. Such binary systems are observed see X-ray binarybut often a supernova explosion will blow the system apart into separate single stars. From Wikipedia, the free encyclopedia. For other uses, see Binary system disambiguation. This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources.
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