Zeta Andromedae (Zeta And, ζ Andromedae, ζ And) is a

star system A star system or stellar system is a small number of stars that orbit each other, bound by gravitational attraction. A large group of stars bound by gravitation is generally called a '' star cluster'' or '' galaxy'', although, broadly speak ...

in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the e ...

Andromeda. It is approximately 189

light-year A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...

s from

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

. Zeta Andromedae is the star's

Bayer designation A Bayer designation is a stellar designation in which a specific star is identified by a Greek or Latin letter followed by the genitive form of its parent constellation's Latin name. The original list of Bayer designations contained 1,564 stars. ...

. It also has the Flamsteed designation 34 Andromedae and multiple other designations in stellar catalogues.

Location

The star's location is in the northern constellation Andromeda, in which it is the second-most southerly of the stars in this often drawn characteristic shape representing the mythical princess asterism, after

η Andromedae Eta Andromedae (Eta And, η Andromedae, η And) is a spectroscopic binary star in the constellation of Andromeda. It consists of two G-type subgiant or giant stars orbiting each other with a period of 115.7 days an ...

System

The system is a

spectroscopic binary A binary star is a system of two star, stars that are gravity, 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 separa ...

whose is classified as an orange K-type giant with a mean

apparent 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 li ...

of +4.08. Due to brightness changes caused by the

ellipsoid An ellipsoid is a surface that may be obtained from a sphere by deforming it by means of directional scalings, or more generally, of an affine transformation. An ellipsoid is a quadric surface; that is, a surface that may be defined as the ...

al shape of that object, the system is also an RS Canum Venaticorum-type

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

. Its brightness varies from magnitude +3.92 to +4.14 with a period of 17.77 days, and its spectrum shows strong and variable Ca II H and K lines. The orbital period of the binary is 17.77 days.

Direct imaging

The primary component of this binary system, ''Zeta Andromedae Aa'', is one of the few stars who has been imaged directly using

Doppler imaging Inhomogeneous structures on stellar surfaces, i.e. temperature differences, chemical composition or magnetic fields, create characteristic distortions in the spectral lines due to the Doppler effect. These distortions will move across spectral li ...

and long-baseline infrared

interferometry Interferometry is a technique which uses the ''interference'' of superimposed waves to extract information. Interferometry typically uses electromagnetic waves and is an important investigative technique in the fields of astronomy, fiber opt ...

. With direct imaging we can recover additional information about this star. Direct imaging also allowed observation of starspots (the analogue to

sunspot Sunspots are phenomena on the Sun's photosphere that appear as temporary spots that are darker than the surrounding areas. They are regions of reduced surface temperature caused by concentrations of magnetic flux that inhibit convection. Sun ...

s), on this star, and their asymmetric distribution showed that the magnetic field of the star is generated by a mechanism different from the

solar dynamo The solar dynamo is a physical process that generates the Sun's magnetic field. It is explained with a variant of the dynamo theory. A naturally occurring electric generator in the Sun's interior produces electric currents and a magnetic field, f ...

. A Sun-like

differential rotation Differential rotation is seen when different parts of a rotating object move with different angular velocities (rates of rotation) at different latitudes and/or depths of the body and/or in time. This indicates that the object is not solid. In flu ...

of the star was observed instead.

Visual companions

The WDS notes three

visual companion In observational astronomy, a double star or visual double is a pair of stars that appear close to each other as viewed from Earth, especially with the aid of optical telescopes. This occurs because the pair either forms a binary star (i.e. a bi ...

s to the eclipsing binary (Aa and Ab, forming binary A). The parallax of the D star has been measured by ''Gaia'' proving its distance to be much greater than Zeta Andromedae, probably a distant red giant. The closest companion, B, is likewise a background object. The companion C at shares a

common proper motion This glossary of astronomy is a list of definitions of terms and concepts relevant to astronomy and cosmology, their sub-disciplines, and related fields. Astronomy is concerned with the study of celestial objects and phenomena that originate outsid ...

and a similar parallax.

Naming

Chinese Chinese can refer to: * Something related to China * Chinese people, people of Chinese nationality, citizenship, and/or ethnicity **''Zhonghua minzu'', the supra-ethnic concept of the Chinese nation ** List of ethnic groups in China, people of va ...

, (), meaning ''

Legs A leg is a weight-bearing and locomotive anatomical structure, usually having a columnar shape. During locomotion, legs function as "extensible struts". The combination of movements at all joints can be modeled as a single, linear element ...

(asterism)'', refers to an asterism consisting of ζ Andromedae,

, 65 Piscium,

ε Andromedae Epsilon Andromedae, Latinized from ε Andromedae, is a star in the constellation of Andromeda. It can be seen with the naked eye, having an apparent visual magnitude of 4.4. Based upon an annual parallax shift of 21.04 ...

δ Andromedae Delta Andromedae, Latinized from δ Andromedae, is a triple star system in the northern constellation of Andromeda. The system is visible to the naked eye as a point of light with a combined apparent visual magnitude of 3.28. Based up ...

π Andromedae Pi Andromedae (Pi And, π Andromedae, π And) is the Bayer designation for a binary star system in the northern constellation of Andromeda. With an apparent visual magnitude of 4.4, it is visible to the naked eye. It i ...

ν Andromedae Nu Andromedae (Nu And, ν Andromedae, ν And) is a binary star in the constellation Andromeda. The system has an apparent visual magnitude of 4.5, which is bright enough to be seen with the naked eye. It is approximately ...

μ Andromedae Mu Andromedae (Mu And, μ Andromedae, μ And) is the Bayer designation for a star in the northern constellation of Andromeda. It has an apparent visual magnitude of 3.87, making it readily visible to the naked eye. Based ...

, β Andromedae,

σ Piscium Sigma Piscium (Sigma Psc, σ Piscium, σ Psc) is a main-sequence star in the zodiac constellation of Pisces. It has an apparent magnitude of +5.50, meaning it is barely visible to the naked eye, according to the Bortle ...

, τ Piscium,

91 Piscium This is the list of notable stars in the constellation Pisces, sorted by decreasing brightness. See also *List of stars by constellation References * * * * * {{Stars of Pisces *List Pisces Pisces may refer to: * Pisces, an obsolete (beca ...

, υ Piscium,

φ Piscium Phi Piscium, Latinized from φ Piscium, is a quadruple star system approximately 380 light years away in the constellation Pisces. It consists of Phi Piscium A, with a spectral type of K0III, and Phi Piscium B. Phi Piscium A posses ...

, χ Piscium and ψ¹ Piscium. Consequently, the Chinese name for ζ Andromedae itself is (, en, the Second Star of Legs).

Notes

References

External links

Zeta Andromedae
at Alcyone Software's Star Data Pages
Image ζ Andromedae
* Rachael Roettenbacher
"How the face of a distant star reveals our place in the cosmos
" Aeon Magazine etrieved July 27, 2016 {{DEFAULTSORT:Zeta Andromedae Andromeda (constellation) K-type giants Andromedae, Zeta Andromedae, 34 004502 003693 Spectroscopic binaries RS Canum Venaticorum variables Rotating ellipsoidal variables 5 BD+23 0106 K-type main-sequence stars 0215