9 Andromedae, abbreviated 9 And by convention, is a

variable Variable may refer to: * Variable (computer science), a symbolic name associated with a value and whose associated value may be changed * Variable (mathematics), a symbol that represents a quantity in a mathematical expression, as used in many ...

binary star system in the northern constellation Andromeda. ''9 Andromedae'' is the

Flamsteed designation A Flamsteed designation is a combination of a number and constellation name that uniquely identifies most naked eye stars in the modern constellations visible from southern England. They are named for John Flamsteed who first used them while co ...

, while it bears the

variable star designation In astronomy, a variable star designation is a unique identifier given to variable stars. It uses a variation on the Bayer designation format, with an identifying label (as described below) preceding the Latin genitive of the name of the conste ...

AN Andromedae, or AN And. The maximum

apparent visual magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's lig ...

of the system is 5.98, which places it near the lower limit of visibility to the human eye. Based upon an annual parallax shift of , it is located 460 light years from the Earth. This system was determined to be a single-lined spectroscopic binary in 1916 by American astronomer W. S. Adams, and the initial orbital elements were computed by Canadian astronomer R. K. Young in 1920. The pair orbit each other with a

period Period may refer to: Common uses * Era, a length or span of time * Full stop (or period), a punctuation mark Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (or rhetorical period), a concept ...

of 3.2196 days and an

eccentricity Eccentricity or eccentric may refer to: * Eccentricity (behavior), odd behavior on the part of a person, as opposed to being "normal" Mathematics, science and technology Mathematics * Off-Centre (geometry), center, in geometry * Eccentricity (g ...

of 0.03. It is an

eclipsing binary A binary star is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved using a telescope as separate stars, in w ...

, which means the

orbital plane The orbital plane of a revolving body is the geometric plane in which its orbit lies. Three non-collinear points in space suffice to determine an orbital plane. A common example would be the positions of the centers of a massive body (host) an ...

is inclined close to the

line of sight The line of sight, also known as visual axis or sightline (also sight line), is an imaginary line between a viewer/observer/ spectator's eye(s) and a subject of interest, or their relative direction. The subject may be any definable object taken ...

and, from the perspective of the Earth, the stars pass in front of each other, causing two partial eclipses every orbit. During the

transit Transit may refer to: Arts and entertainment Film * ''Transit'' (1979 film), a 1979 Israeli film * ''Transit'' (2005 film), a film produced by MTV and Staying-Alive about four people in countries in the world * ''Transit'' (2006 film), a 2006 ...

of the secondary in front of the primary, the visual magnitude drops to 6.16, while the eclipse of the secondary by the primary lowers the net magnitude to 6.09.

References

External links

Image 9 Andromedae
{{DEFAULTSORT:9 Andromedae AN Andromedae

9 Andromedae 9 Andromedae, abbreviated 9 And by convention, is a variable binary star system in the northern constellation Andromeda. ''9 Andromedae'' is the Flamsteed designation, while it bears the variable star designation AN Andromedae, or AN ...

Durchmusterung objects Andromedae, 09 219815 115065 8864 Andromedae, AN Eclipsing binaries A-type main-sequence stars