SS Cygni
Encyclopedia
SS Cygni is a variable star in the northern constellation Cygnus
(the Swan). It is classified as a dwarf nova
, meaning that it undergoes frequent and regular brightness outbursts - every 7 or 8 weeks in the case of this much-observed example. SS Cygni is often classified as a U Geminorum
type dwarf nova. However, the maxima of SS Cygni are typically brighter than those of U Gem, rising from 12th magnitude to 8th magnitude for, typically, 1–2 days. The northerly declination
of SS Cygni (44N) makes the star is almost circumpolar from European and North American latitudes, allowing a large proportion of the world's amateur astronomers to monitor its behaviour. Furthermore, since the star lies against the rich backdrop of the Milky Way
band, the telescope field of view around SS Cygni contains an abundance of useful brightness comparison stars.
Cygnus (constellation)
Cygnus is a northern constellation lying on the plane of the Milky Way. Its name is the Latinized Hellenic word for swan. One of the most recognizable constellations of the northern summer and autumn, it features a prominent asterism known as the Northern Cross...
(the Swan). It is classified as a dwarf nova
Dwarf nova
A U Geminorum-type variable star, or dwarf nova is a type of cataclysmic variable starhttp://www.sai.msu.su/groups/cluster/gcvs/gcvs/iii/vartype.txt consisting of a close binary star system in which one of the components is a white dwarf, which accretes matter from its companion...
, meaning that it undergoes frequent and regular brightness outbursts - every 7 or 8 weeks in the case of this much-observed example. SS Cygni is often classified as a U Geminorum
U Geminorum
U Geminorum , in the constellation Gemini, is an archetypal example of a dwarf nova. The binary star system consists of a white dwarf closely orbiting a red dwarf. Roughly every 100 days it undergoes an outburst that greatly increases its brightness. Discovered by J.R...
type dwarf nova. However, the maxima of SS Cygni are typically brighter than those of U Gem, rising from 12th magnitude to 8th magnitude for, typically, 1–2 days. The northerly declination
Declination
In astronomy, declination is one of the two coordinates of the equatorial coordinate system, the other being either right ascension or hour angle. Declination in astronomy is comparable to geographic latitude, but projected onto the celestial sphere. Declination is measured in degrees north and...
of SS Cygni (44N) makes the star is almost circumpolar from European and North American latitudes, allowing a large proportion of the world's amateur astronomers to monitor its behaviour. Furthermore, since the star lies against the rich backdrop of the Milky Way
Milky Way
The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...
band, the telescope field of view around SS Cygni contains an abundance of useful brightness comparison stars.