Changes
Added info on Optical and Cataclysmic binaries
If sufficient measurements and observations of the visible star's movement over time can be made, it is possible to determine the masses of both stars using [[Kepler|Kepler's laws]].<ref>http://csep10.phys.utk.edu/astr162/lect/binaries/astrometric.html</ref>
===Optical Binaries===
An optical binary are two stars that visually appear next to each other from the point of the observer using the unaided eye. The reason for this is the two stars are usually along the line of sight of the observer, giving the illusion they are part of a binary pair. However in reality the two stars are actually a great distance from each other and are not gravitationally bound as a single system. A prime example of this is [[Alpha Capricorni]], traditionally seen as a binary with the individual stars referred to as α<sup>1</sup> Capricorni and α<sup>2</sup> Capricorni, however the former is 690 light years away, while the latter is only 109 light years away from [[Earth]] respectively.
==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]].
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://www.daviddarling.info/encyclopedia/C/cataclysmic_binary.html</ref>
==History==
