Editing Variable star (section)

====Dwarf novae====
{{Main|Dwarf nova}}
Dwarf novae are double stars involving a [[white dwarf]] in which matter transfer between the component gives rise to regular outbursts. There are three types of dwarf nova:
* [[U Geminorum star]]s, which have outbursts lasting roughly 5–20 days followed by quiet periods of typically a few hundred days. During an outburst they brighten typically by 2–6 magnitudes. These stars are also known as [[SS Cygni variable]]s after the variable in [[Cygnus (constellation)|Cygnus]] which produces among the brightest and most frequent displays of this variable type.
* [[Z Camelopardalis star]]s, in which occasional plateaux of brightness called ''standstills'' are seen, part way between maximum and minimum brightness.
* [[SU Ursae Majoris star]]s, which undergo both frequent small outbursts, and rarer but larger ''[[superoutburst]]s''. These binary systems usually have orbital periods of under 2.5 hours.