Editing Cataclysmic variable star (section)

== Classification ==
Cataclysmic variables are subdivided into several smaller groups, often named after a bright prototype star characteristic of the class. In some cases the [[magnetic field]] of the white dwarf is strong enough to disrupt the inner accretion disk or even prevent disk formation altogether. Magnetic systems often show strong and variable [[Polarization (waves)|polarization]] in their optical light, and are therefore sometimes called [[polar (cataclysmic variable)|polars]]; these often exhibit small-amplitude brightness fluctuations at what is presumed to be the white dwarf's period of rotation.

{| class="wikitable"
| [[Supernova]]e
| These are classed as cataclysmic variables and have extremely large outbursts that destroy the progenitor star.  Some result from white dwarfs in binary systems but others are very massive stars.
|-
| (Classical) [[nova]]e
| These cataclysmic variables have very large outbursts, of 6 to 19 magnitudes, caused by thermonuclear fusion of material accreted onto the white dwarf.
|-
| Recurrent novae
| These have outbursts of about 4 to 9 magnitudes, repeating every 10 to 80 years.<ref>{{cite book|page=[https://archive.org/details/cataclysmiccosmi00mobb/page/n70 59]|title=Cataclysmic Cosmic Events and How to Observe Them|url=https://archive.org/details/cataclysmiccosmi00mobb|url-access=limited|first=Martin|last=Mobberley|location=New York|publisher=Springer|date=2009|isbn=978-0-387-79945-2}}</ref> Examples include [[T Pyxidis]] and [[RS Ophiuchi]].
|-
| [[Dwarf nova]]e
| Dwarf novae, or [[U Geminorum star]]s, are cataclysmic variables which are observed to brighten repeatedly, though by a smaller amount than classical novae.
{|
|-
| [[Z Camelopardalis star]]s
| Temporarily "halt" at a particular brightness below their peak
|-
| [[SU Ursae Majoris star]]s
| Have "[[superoutburst]]s" which are brighter than the average
|-
| [[SS Cygni star]]s
| Have outbursts of two distinct lengths
|}
|-
| [[Luminous red nova]]e
| These are stellar mergers that become very red after outburst.
|-
| [[polar (cataclysmic variable)|Polars]]
|
{|
|-
| [[AM Herculis variable|AM Herculis]] stars are binaries in which the magnetic field of the white dwarf has synchronized the latter's rotational period with the binary orbital period. Matter from the donor star is magnetically channeled onto the white dwarf rather than forming a disc.
|-
| [[DQ Herculis variable|DQ&nbsp;Herculis]], also called 'intermediate polars', have a slightly weaker magnetic field than [[AM Herculis]] stars; there is an accretion disc, but substructure in it is created by the field.
|}
|-
| [[VY Sculptoris variable|VY Sculptoris]]
| These are stars which occasionally drop in brightness by more than one magnitude, with very occasional dwarf-nova-type outbursts during the dim state. They may be a subclass of polars.<ref>{{cite journal|first1=Jean-Marie|last1=Hameury|first2=Jean-Pierre|last2=Lasota|journal=[[Astronomy and Astrophysics]]|arxiv=astro-ph/0207084|title=VY Sculptoris stars as magnetic CVs|volume=394|issue=1|pages=231–239|date=October 4, 2002|doi=10.1051/0004-6361:20021136|bibcode=2002A&A...394..231H|s2cid=5498393}}</ref>
|-
| [[AM Canum Venaticorum variable|AM Canum Venaticorum]]
| These are cataclysmic variables both of whose components are white dwarfs; the accretion disc is composed primarily of helium, and they are of interest as sources of [[gravitational waves]].
|-
| [[SW Sextantis variable|SW Sextantis]]
| These are like dwarf novae but have the accretion disc in a steady state, so do not show outbursts; the disc emits non-uniformly. They are usually also [[Eclipsing variable#Eclipsing binaries|eclipsing variables]], though this appears to be a [[selection artefact]].<ref>{{cite web|title=Defining Characteristics of the SW Sextantis Stars|url=http://spider.ipac.caltech.edu/staff/hoard/research/swsex/characteristics.html|url-status=dead|archive-url=https://web.archive.org/web/20071119022732/http://spider.ipac.caltech.edu/staff/hoard/research/swsex/characteristics.html|archive-date=2007-11-19}}</ref>
|-
| [[Z Andromedae]] (symbiotic variables)
| These are close binaries with a large cool component losing mass to a hotter compact component and accretion disc.
|}

There are over 1600 known CV systems.<ref>{{cite web|url=http://archive.stsci.edu/prepds/cvcat/index.html|title=A Catalog and Atlas of Cataclysmic Variables|first1=Ronald|last1=Downes|author2=<!-- cited as such at the URL --> |display-authors=etal}}</ref> The catalog was frozen as of 1 February 2006 though more are discovered each year.