Eta Aurigae (η Aurigae, abbreviated Eta Aur, η Aur), officially named Haedus , is a

star A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...

in the

northern Northern may refer to the following: Geography * North, a point in direction * Northern Europe, the northern part or region of Europe * Northern Highland, a region of Wisconsin, United States * Northern Province, Sri Lanka * Northern Range, a r ...

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

Auriga AURIGA (''Antenna Ultracriogenica Risonante per l'Indagine Gravitazionale Astronomica'') is an ultracryogenic resonant bar gravitational wave detector in Italy. It is at the Laboratori Nazionali di Legnaro of the Istituto Nazionale di Fisica Nuclea ...

. With an

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 3.18, it is 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 lines of sight and is measured by the angle or semi-angle of inclination between those two lines. Due to foreshortening, nearby object ...

measurements made during the ''

Hipparcos ''Hipparcos'' was a scientific satellite of the European Space Agency (ESA), launched in 1989 and operated until 1993. It was the first space experiment devoted to precision astrometry, the accurate measurement of the positions of celestial ob ...

'' mission, this star is approximately distant from the

Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...

Nomenclature

''η Aurigae'' ( Latinised to ''Eta Aurigae'') 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 ...

. Along with Zeta Aurigae it represents one of the kids of the she-goat

Capella Capella is the brightest star in the northern constellation of Auriga. It has the Bayer designation α Aurigae, which is Latinised to Alpha Aurigae and abbreviated Alpha Aur or α Aur. Capella is the sixth-brightest star in ...

, from which it derived its

Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through ...

traditional name ''Haedus II'' or ''Hoedus II'', from the Latin ''haedus'' "kid" (Zeta Aurigae was Haedus I). It also had the less common traditional name ''Mahasim,'' from the

Arabic Arabic (, ' ; , ' or ) is a Semitic language spoken primarily across the Arab world.Semitic languages: an international handbook / edited by Stefan Weninger; in collaboration with Geoffrey Khan, Michael P. Streck, Janet C. E.Watson; Walter ...

المِعْصَم ''al-miʽşam'' "the wrist" (of the charioteer), which it shared with Theta Aurigae. In 2016, the IAU organized a

Working Group on Star Names The International Astronomical Union (IAU) established a Working Group on Star Names (WGSN) in May 2016 to catalog and standardize proper names for stars for the international astronomical community. It operates under Division C – Education ...

(WGSN) to catalog and standardize proper names for stars. The WGSN approved the names ''Haedus'' for Eta Aurigae and ''Saclateni'' for Zeta Aurigae A on 30 June 2017 and they are both now so included in the List of IAU-approved Star Names. In Chinese, (), meaning ''

Pillars A column or pillar in architecture and structural engineering is a structural element that transmits, through compression, the weight of the structure above to other structural elements below. In other words, a column is a compression member. ...

'', refers to an asterism consisting of Eta Aurigae,

Epsilon Aurigae Epsilon Aurigae (ε Aurigae, abbreviated Epsilon Aur, ε Aur) is a multiple star system in the northern constellation of Auriga, the charioteer. It is an unusual eclipsing binary system comprising an F0 supergiant (officially named Alma ...

, Zeta Aurigae,

Upsilon Aurigae Upsilon Aurigae, Latinised from υ Aurigae, is the Bayer designation for a single star in the northern constellation of Auriga. It has an apparent visual magnitude of 4.74, which means it is bright enough to be seen with the naked eye ...

Nu Aurigae Nu Aurigae, Latinised from ν Aurigae, is the Bayer designation for a star in the northern constellation of Auriga. It is visible to the naked eye with an apparent visual magnitude of 3.96 and is approximately distant from the Earth. ...

Tau Aurigae Tau Aurigae, Latinized from τ Aurigae, is a star in the northern constellation Auriga. It is visible to the naked eye with an apparent visual magnitude of 4.505, and is approximately distant from Earth. Tau Aurigae is an evolved gia ...

Chi Aurigae Chi Aurigae, Latinized from χ Aurigae, is the Bayer designation for a binary star system in the northern constellation of Auriga. It is faintly visible to the naked eye with an apparent visual magnitude of 4.74. The annual parallax shi ...

and

26 Aurigae 26 Aurigae is a binary star system in the northern constellation of Auriga. It is visible to the naked eye as a faint star with an apparent visual magnitude of 5.41. The distance to this system remains poorly constrained. The new Hippar ...

. Consequently, the

Chinese name Chinese names or Chinese personal names are names used by individuals from Greater China and other parts of the Chinese-speaking world throughout East and Southeast Asia (ESEA). In addition, many names used in Japan, Korea and Vietnam are ofte ...

for Eta Aurigae itself is (, en, the Third Star of Pillars).香港太空館 - 研究資源 - 亮星中英對照表
, Hong Kong Space Museum. Accessed on line November 23, 2010.

Properties

Since 1943, the

spectrum A spectrum (plural ''spectra'' or ''spectrums'') is a condition that is not limited to a specific set of values but can vary, without gaps, across a continuum. The word was first used scientifically in optics to describe the rainbow of colors ...

of Eta Aurigae has served as one of the stable anchor points by which other stars are classified. Eta Aurigae is a larger star than the

, with more than five times the

Sun's mass The solar mass () is a standard unit of mass in astronomy, equal to approximately . It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxies and black holes. It is approximately equal to the mass of ...

and over three times its radius. The spectrum of this star matches a

stellar classification In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the ...

of B3 V, which is a

B-type main-sequence star A B-type main-sequence star (B V) is a main-sequence ( hydrogen-burning) star of spectral type B and luminosity class V. These stars have from 2 to 16 times the mass of the Sun and surface temperatures between 10,000 and 30,000 K. B-type st ...

that is generating its energy through the

nuclear fusion Nuclear fusion is a reaction in which two or more atomic nuclei are combined to form one or more different atomic nuclei and subatomic particles ( neutrons or protons). The difference in mass between the reactants and products is manife ...

hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-to ...

at its core. It is radiating 955 times the

Sun's luminosity The solar luminosity (), is a unit of radiant flux (power emitted in the form of photons) conventionally used by astronomers to measure the luminosity of stars, galaxies and other celestial objects in terms of the output of the Sun. One nominal ...

from its outer atmosphere 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 . Based upon its

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 bulge ...

of 95, it is spinning with a rotation period of only 1.8 days. Eta Aurigae is around 39 million years old.

References

External links

HR 1641

Image Eta Aurigae
{{DEFAULTSORT:Eta Aurigae 032630 023767 Aurigae, Eta Auriga (constellation) B-type main-sequence stars Haedus Aurigae, 10

1641 Events January–March * January 4 – The stratovolcano Mount Parker in the Philippines) has a major eruption. * January 18 – Pau Claris proclaims the Catalan Republic. * February 16 – King Charles I of England gi ...

Durchmusterung objects