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An eclipsing binary is a binary system where the orbital plain is close enough to the line of sight of an observer that the individual stars will [[eclipse]] each other.   

An eclipsing binary is a binary system where the orbital plain is close enough to the line of sight of an observer that the individual stars will [[eclipse]] each other.   

Eclipsing binaries are also classified as [[variable stars|variable stars]], stars that have regular and periodic changes in the apparent magnitude.  This variation in brightness may be from a pair of binary stars as one passes in front of the other as seen from the point of the observer.  If the two stars are of different sizes, the larger star will block the other through a total eclipse, while the smaller star will partially dim the large one via an annular eclipse.  This change in brightness over regular periods of time is known as the ''light curve''.<ref>http://www.physics.sfasu.edu/astro/ebstar/ebstar.html</ref>

Eclipsing binaries are also classified as [[variable stars]], stars that have regular and periodic changes in the apparent magnitude.  This variation in brightness may be from a pair of binary stars as one passes in front of the other as seen from the point of the observer.  If the two stars are of different sizes, the larger star will block the other through a total eclipse, while the smaller star will partially dim the large one via an annular eclipse.  This change in brightness over regular periods of time is known as the ''light curve''.<ref>http://www.physics.sfasu.edu/astro/ebstar/ebstar.html</ref>

The first observed eclipsing binary discovered was the star system [[Algol]].  The star was known to periodically change in magnitude since ancient times, but in 1881, it was discovered this was due to the fact Algol was not one, but two stars in close orbit.

The first observed eclipsing binary discovered was the star system [[Algol]].  The star was known to periodically change in magnitude since ancient times, but in 1881, it was discovered this was due to the fact Algol was not one, but two stars in close orbit.

==Cataclysmic Binary==

==Cataclysmic Binary==

Cataclysmic binaries, sometimes referred to as ''cataclysmic variable stars'' or ''cataclysmic variables'', are very close binary pair that will suddenly and irregularly increase in brightness before returning to their normal magnitude.  The two components of a cataclysmic binary consist of a [[white dwarf]] primary and an M class secondary (ranging from a main sequence star to a giant).  The two stars are sufficiently close that the white dwarf distorts and draws off material from the secondary.  This infalling matter of mostly [[hydrogen]] forms an accretion disk around the white dwarf.  Instabilities in this accretion disk can lead to what is known as a [[Nova_(star)#Dwarf_Novae|dwarf nova]].

Cataclysmic binaries, sometimes referred to as ''cataclysmic variable stars'' or ''cataclysmic variables'', are very close binary pair that will suddenly and irregularly increase in brightness before returning to their normal magnitude.  The two components of a cataclysmic binary consist of a [[white dwarf]] primary and an M class secondary (ranging from a main sequence star to a giant).  The two stars are sufficiently close that the white dwarf distorts and draws off material from the secondary.  This infalling matter of mostly [[hydrogen]] forms an accretion disk around the white dwarf.  Instabilities in this accretion disk can lead to what is known as a [[Nova (star)#Dwarf Novae|dwarf nova]].

There are two types of cataclysmic binaries, non-magnetic and [[magnetic]].  The non-magnetic types are by far the most common, these include [[Nova_(star)#Dwarf_Novae|U Geminorum stars]] as well as those that are the source of [[Nova_(star)|classical and recurrent novae]].  Much more rare are the magnetic types, where a powerful magnetic field surrounds the primary white dwarf star, greatly affecting how the material flows from the secondary star, as well as locking the two stars into a synchronous rotation.<ref>

There are two types of cataclysmic binaries, non-magnetic and [[magnetic]].  The non-magnetic types are by far the most common, these include [[Nova (star)#Dwarf Novae|U Geminorum stars]] as well as those that are the source of [[Nova (star)|classical and recurrent novae]].  Much more rare are the magnetic types, where a powerful magnetic field surrounds the primary white dwarf star, greatly affecting how the material flows from the secondary star, as well as locking the two stars into a synchronous rotation.<ref>

*http://heasarc.gsfc.nasa.gov/docs/objects/cvs/cvstext.html

*http://heasarc.gsfc.nasa.gov/docs/objects/cvs/cvstext.html

*http://www.daviddarling.info/encyclopedia/C/cataclysmic_binary.html</ref>

*http://www.daviddarling.info/encyclopedia/C/cataclysmic_binary.html</ref>

===Type I supernova===

===Type I supernova===

If one of the stars on a binary system is a [[white dwarf]] that is close enough to its companion when the companion star exceeds its Roche lobe, the white dwarf will steadily accrete gases from its companion's atmosphere. This accreted gases will build up and compress on the surface of the white dwarf, due to its high gravity at its surface.  The gas will then steadily heat up as more material accumulates.  The result is that [[hydrogen]] fusion may occur on the surface of the dwarf and, through the tremendous release in energy, throw the rest of the collected gas off in a brilliant flash.  This extremely bright event is called a [[nova]]. <ref>D. Prialnik, Novae, Encyclopaedia of Astronomy and Astrophysics (2001, p.1846-1856)</ref>

If one of the stars on a binary system is a [[white dwarf]] that is close enough to its companion when the companion star exceeds its Roche lobe, the white dwarf will steadily accrete gases from its companion's atmosphere. This accreted gases will build up and compress on the surface of the white dwarf, due to its high gravity at its surface.  The gas will then steadily heat up as more material accumulates.  The result is that [[hydrogen]] fusion may occur on the surface of the dwarf and, through the tremendous release in energy, throw the rest of the collected gas off in a brilliant flash.  This extremely bright event is called a [[nova]].<ref>D. Prialnik, Novae, Encyclopaedia of Astronomy and Astrophysics (2001, p.1846-1856)</ref>

The above event will occur as long as the additional mass the white dwarf accreted from its companion doesn't cause the star to exceed the [[Chandrasekhar limit]], which is 1.4 solar masses.  If the material buildup on the white dwarf exceeds this limit, the electron degeneracy of the white dwarf itself will no longer be able to hold the star up against gravity.  In this scenario a type I [[supernova]] will occur that destroys the star.  The most famous example of this is the supernova [[SN 1572]], considered one of the foremost events in astronomy.  [[Tycho Brahe]] observed this event extensively.<ref name="psu">http://www.astro.psu.edu/users/rbc/a1/lec16n.html</ref>

The above event will occur as long as the additional mass the white dwarf accreted from its companion doesn't cause the star to exceed the [[Chandrasekhar limit]], which is 1.4 solar masses.  If the material buildup on the white dwarf exceeds this limit, the electron degeneracy of the white dwarf itself will no longer be able to hold the star up against gravity.  In this scenario a type I [[supernova]] will occur that destroys the star.  The most famous example of this is the supernova [[SN 1572]], considered one of the foremost events in astronomy.  [[Tycho Brahe]] observed this event extensively.<ref name="psu"/>

[[Category: Astronomy]]

[[Category:Astronomy]]

== External links ==

== External links ==