Binary star Reference Libraries

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Lyra Constellation
2004-10-19 04:45:44

Lyra Constellation -- Lyra (the lyre) is a prominent, although fairly small, northern constellation. It was one of Ptolemy's 48 constellations, and also counts among the modern 88 constellations. Its brightest star is Vega (Alpha Lyrae), which together with Altair (Alpha Aquilae) and Deneb (Alpha Cygni) forms the large asterism known as the Summer Triangle. Beta Lyr is a half separated...

X-ray Burster
2004-10-19 04:45:43

X-ray Burster -- X-ray bursters are a class of binary stars which are luminous in X-rays. They contain a neutron star and a low-mass companion star. The companion fills its Roche lobe and therefore the neutron star is accreting matter from it. The inflowing gas forms an accretion disk around the neutron star. Sometimes X-ray bursters show a sudden increase in their X-ray luminosity, called...

X-ray Binaries
2004-10-19 04:45:43

X-ray Binaries -- X-ray binaries are a class of binary stars that are very luminous in X-rays. The X-rays are produced by matter falling from one component (usually a relatively normal star) to the other component, which is a neutron star or a black hole. The infalling matter releases gravitational potential energy, up to several tens of per cent of its rest mass as X-rays. (Hydrogen...

Variable Star
2004-10-19 04:45:43

Variable Star -- Most stars are of nearly constant luminosity. Our own Sun is a good example which goes through practically no measurable variation in brightness. There are, however, stars which do vary in brightness, called variable stars. They fall into two main groups: Intrinsic variables These are stars which have intrinsic variations in brightness, that is the star itself gets...

Triple Star
2004-10-19 04:45:42

Triple Star -- A triple star system consists of three gravitationally bound stars. The stars are in orbits around a common center of mass, usually so that two of the stars form a close binary star and the third is further away. This configuration is often called a hierarchical triple star. Multiple stars containing more than three stars can usually be decomposed to binaries and...

2004-10-19 04:45:42

Nova -- A nova is an enormous nuclear explosion caused by the accretion of hydrogen onto the surface of a white dwarf star. When a white dwarf has a close companion star, the companion will often begin to have its outer atmosphere drawn away from it by the white dwarf's gravity as the companion star ages and expands into a red giant. The gases so captured consist primarily of hydrogen...

Double Star
2004-10-19 04:45:41

Double Star -- When two stars are so nearly in the same direction as seen from Earth that they appear to be a single star to the naked eye but may be separated by the use of telescopes, they are referred to as a double star. There are two different kinds of double star. In the case where two stars are only apparently close to each other, but which are in fact separated by a great distance...

Binary Star
2004-10-19 04:45:41

Binary Star -- A binary star system consists of two stars both orbiting around a gravitational point between them. The term "binary star" was apparently first coined by Sir William Herschel in 1802 to designate "a real double star - the union of two stars that are formed together in one system by the laws of attraction." At present, binary stars are classified into three types according...

Accretion Disk
2004-10-19 04:45:41

Accretion Disk -- An accretion disk is a structure formed by material falling into a gravitational source. Conservation of angular momentum requires that, as a large cloud of material collapses inward, any small rotation it may have will increase. Centrifugal force causes the rotating cloud to collapse into a disk, and tidal effects will tend to align this disk's rotation with the rotation...

Alpha Centauri
2004-10-19 04:45:40

Alpha Centauri -- Alpha Centauri is the brightest star system in the southern constellation of Centaurus, and is the third brightest in the entire night sky (although too far south to be visible in most of the northern hemisphere). It is also the closest star system to Earth. It bears the proper name Rigil Kentaurus (often shortened to Rigil Kent), meaning "foot of the centaur" in Arabic,...

Word of the Day
  • A unit of saved energy.
Coined by Amory Lovins, chairman of the Rocky Mountain Institute as a contraction of negative watt on the model of similar compounds like megawatt.