R Cygni is a

variable star A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes systematically with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are ...

of the

Mira Mira (), designation Omicron Ceti (ο Ceti, abbreviated Omicron Cet, ο Cet), is a red-giant star estimated to be 200–300 light-years from the Sun in the constellation Cetus. ο Ceti is a binary stellar system, consisting of a vari ...

type in the constellation Cygnus, less than 4' from θ Cygni. This is a

red giant A red giant is a luminous giant star of low or intermediate mass (roughly 0.3–8 solar masses ()) in a late phase of stellar evolution. The stellar atmosphere, outer atmosphere is inflated and tenuous, making the radius large and the surface t ...

star on the

asymptotic giant branch The asymptotic giant branch (AGB) is a region of the Hertzsprung–Russell diagram populated by evolved cool luminous stars. This is a period of stellar evolution undertaken by all low- to intermediate-mass stars (about 0.5 to 8 solar masses) lat ...

located around 2,200

light year A light-year, alternatively spelled light year (ly or lyr), is a unit of length used to express astronomical distance, astronomical distances and is equal to exactly , which is approximately 9.46 trillion km or 5.88 trillion mi. As defined by t ...

s away. It is an

S-type star An S-type star (or just S star) is a cool giant star with approximately equal quantities of carbon and oxygen in its atmosphere. The class was originally defined in 1922 by Paul Merrill for stars with unusual absorption lines and molecular bands ...

ranging between spectral types S2.5,9e to S6,9e(Tc). Stars at this mass range and

evolutionary Evolution is the change in the heritable characteristics of biological populations over successive generations. It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, resulting in certa ...

stage are pulsationally unstable, displaying a variation in their light output. R Cygni has a maximum

magnitude Magnitude may refer to: Mathematics *Euclidean vector, a quantity defined by both its magnitude and its direction *Magnitude (mathematics), the relative size of an object *Norm (mathematics), a term for the size or length of a vector *Order of ...

of 6.1 and a minimum magnitude of 14.4, with a period of 426.45 days. The variation of this star was discovered by English astronomer N. R. Pogson in 1852, and it has a history of recorded brightness measurements stretching back more than a century. R Cygni shows distinct period-doubling, where alternate maxima are of different brightness, hence the real period of pulsation could be considered to be twice that from one maximum to the next. The

Catalog of Components of Double and Multiple Stars The Catalog of Components of Double and Multiple Stars, or CCDM, is an astrometry, astrometric star catalogue of double star, double and multiple star, multiple stars. It was made by Jean Dommanget and Omer Nys at the Observatoire Royal de Belgiq ...

lists 10th magnitude BD+49 3065 as a companion to R Cygni, at a separation of 91", and both stars lie at approximately the same distance. The

Washington Double Star Catalog The Washington Double Star Catalog, or WDS, is a catalog of double stars, maintained at the United States Naval Observatory. The catalog contains positions, magnitudes, proper motions and spectral types and has entries for (as of January 2024) 1 ...

additionally lists a 15th magnitude star as a companion at a separation of about 14".

References

{{Stars of Cygnus S-type stars Mira variables Cygnus (constellation) Durchmusterung objects 185456 031822 Cygni, R Emission-line stars

See also

References