Mu Andromedae is a

binary star A binary star or binary star system 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 as separate stars us ...

system in the northern

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 first constellati ...

of Andromeda. Its

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

is Latinized from μ Andromedae, and abbreviated Mu And or μ And, respectively. The system has an

apparent visual magnitude Apparent magnitude () is a measure of the brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction of the object's light ca ...

of 3.87, making it readily visible to the naked eye. Based upon

parallax Parallax is a displacement or difference in the apparent position of an object viewed along two different sightline, lines of sight and is measured by the angle or half-angle of inclination between those two lines. Due to perspective (graphica ...

measurements, it is located at a distance of approximately from

Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...

. In the constellation, the star is situated about halfway between the bright star Mirach to the southwest and the

Andromeda Galaxy The Andromeda Galaxy is a barred spiral galaxy and is the nearest major galaxy to the Milky Way. It was originally named the Andromeda Nebula and is cataloged as Messier 31, M31, and NGC 224. Andromeda has a Galaxy#Isophotal diameter, D25 isop ...

(M31) to the northeast. The

spectrum A spectrum (: spectra or spectrums) is a set of related ideas, objects, or properties whose features overlap such that they blend to form a continuum. The word ''spectrum'' was first used scientifically in optics to describe the rainbow of co ...

of this star matches a

stellar classification In astronomy, stellar classification is the classification of stars based on their stellar spectrum, spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a Prism (optics), prism or diffraction gratin ...

of A5 V, indicating that it is an

A-type main sequence star An A-type main-sequence star (A) or A dwarf star is a main-sequence (hydrogen burning) star of spectral type A and luminosity class (five). These stars have spectra defined by strong hydrogen Balmer absorption lines. They measure between 1.7 ...

. It has 2.2 times the mass of the Sun and three times the Sun's radius. The star is radiating about 40 times the luminosity of the Sun from its outer envelope at an

effective temperature The effective temperature of a body such as a star or planet is the temperature of a black body that would emit the same total amount of electromagnetic radiation. Effective temperature is often used as an estimate of a body's surface temperature ...

of 8,320 K, giving it the characteristic white glow of an A-type star. It is estimated to be about 724 million years old, with a relatively high

projected rotational velocity Stellar rotation is the angular motion of a star about its axis. The rate of rotation can be measured from the spectrum of the star, or by timing the movements of active features on the surface. The rotation of a star produces an equatorial bu ...

of 75 km/s. In 2007, Mu Andromedae was found to be a tidally-locked close

binary system A binary system is a system of two astronomical bodies of the same kind that are comparable in size. Definitions vary, but typically require the center of mass to be located outside of either object. (See animated examples.) The most common ki ...

with an unseen companion. The two stars orbit each other every 550.7 days. The tidal interactions have spun up the primary star, causing it to become magnetically active and host unusually strong

starspot Starspots are stellar phenomena, so-named by analogy with sunspots. Spots as small as sunspots have not been detected on other stars, as they would cause undetectably small fluctuations in brightness. The commonly observed starspots are in gene ...

Naming

In Chinese, (), 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 cap ...

(asterism)'', refers to an asterism consisting of μ Andromedae, η Andromedae,

65 Piscium This is the list of notable stars 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, mythologi ...

, ζ Andromedae, ε Andromedae, δ Andromedae, π Andromedae, ν Andromedae, β Andromedae,

σ Piscium Sigma Piscium (Sigma Psc, σ Piscium, σ Psc) is a binary 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 scale ...

τ Piscium Tau Piscium (τ Piscium) is an orange-hued star in the zodiac constellation of Pisces. With an apparent visual magnitude of +4.52, it is a dim star but visible to the naked eye. Based upon an annual parallax shift of 19.32 ...

, 91 Piscium, υ Piscium, φ Piscium, χ Piscium and ψ¹ Piscium. Consequently, the

Chinese name Chinese may refer to: * Something related to China * Chinese people, people identified with China, through nationality, citizenship, and/or ethnicity **Han Chinese, East Asian ethnic group native to China. **'' Zhonghua minzu'', the supra-ethni ...

for μ Andromedae itself is (, .)AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 19 日

References

External links

* http://www.alcyone-software.com/cgi-bin/search.pl?object=HR0269
Image μ Andromedae
{{DEFAULTSORT:Mu Andromedae A-type main-sequence stars RS Canum Venaticorum variables Binary stars Andromeda (constellation) Andromedae, Mu 0269 BD+37 0175 Andromedae, 37 005448 004436