Gamma Tauri (γ Tauri, abbreviated Gamma Tau, γ Tau) is either a solitary,

binary Binary may refer to: Science and technology Mathematics * Binary number, a representation of numbers using only two digits (0 and 1) * Binary function, a function that takes two arguments * Binary operation, a mathematical operation that t ...

double star 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 ...

(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 June 2017) 141,7 ...

notes it as a "Dubious Double" or "Bogus Binary") that marks the tip of the "V" 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 ...

Taurus Taurus is Latin for 'bull' and may refer to: * Taurus (astrology), the astrological sign * Taurus (constellation), one of the constellations of the zodiac * Taurus (mythology), one of two Greek mythological characters named Taurus * ''Bos taurus ...

. It is a member of, and located within about 2.5 parsecs of the center of, the Hyades star cluster, the nearest

open cluster An open cluster is a type of star cluster made of up to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age. More than 1,100 open clusters have been discovered within the Milky Way galaxy, and ...

to the Sun. 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 objects ...

measurements, Gamma Tauri is approximately 154

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 the Sun. Considered as a pair of stars, the two components are designated Gamma Tauri A (officially named Prima Hyadum , the traditional name for the system) and B.

Nomenclature

''γ Tauri'' ( Latinised to ''Gamma Tauri'') is the system'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. ...

. The designations of the two potential components as ''Gamma Tauri A'' and ''B'' derive from the convention used by the Washington Multiplicity Catalog (WMC) for

multiple 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 speaki ...

s, and adopted by the

International Astronomical Union The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreac ...

(IAU). Gamma Tauri bore the traditional name ''Hyadum I'', which is

Latin Latin (, or , ) is a classical language belonging to the 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 the power of the ...

for "First of the Hyades". 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 decided to attribute proper names to individual stars rather than entire multiple systems. It approved the name ''Prima Hyadum'' for the component Gamma Tauri A on 5 September 2017 and it is now so included in the List of IAU-approved Star Names. In

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 '' Net'', refers to an asterism consisting of Gamma Tauri,

Epsilon Tauri Epsilon Tauri or ε Tauri, formally named Ain (), is an orange giant star located approximately 45 parsecs (147 light-years) from the Sun in the constellation of Taurus. An extrasolar planet (designated Epsilon Tauri b, later named Amate ...

, Delta³ Tauri, Delta¹ Tauri, Alpha Tauri (

Aldebaran Aldebaran (Arabic: “The Follower”, "الدبران") is the brightest star in the zodiac constellation of Taurus. It has the Bayer designation α Tauri, which is Latinized to Alpha Tauri and abbreviated Alpha Tau or α Tau. Aldebar ...

71 Tauri 71 Tauri is a suspected triple star system in the zodiac constellation Taurus, located 146 light years from the Sun. It is visible to the naked eye as a faint, yellow-white hued star with an apparent visual magnitude of +4.48. The st ...

and

Lambda Tauri Lambda Tauri (λ Tau, λ Tauri) is a triple star system in the constellation Taurus. In the ''Calendarium of Al Achsasi Al Mouakket'', this star was designated ''Sadr al Tauri'', which was translated into Latin as ''Pectus Tauri'', meanin ...

. Consequently, the Chinese name for γ Tauri itself is (), "the Fourth Star of Net".

Properties

Gamma Tauri presents as a spectral class G8 or K0 giant star with an

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 +3.65. This star has passed through the

main sequence In astronomy, the main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Her ...

phase is now a red clump giant, meaning it is using nuclear fusion of

helium Helium (from el, ἥλιος, helios, lit=sun) is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table. ...

at its core to provide energy. Age estimates for Gamma Tauri range from 430 million to 530 million years. By comparison, the age of the Hyades cluster is about 625 million years with an error margin of 50 million years. The

angular diameter The angular diameter, angular size, apparent diameter, or apparent size is an angular distance describing how large a sphere or circle appears from a given point of view. In the vision sciences, it is called the visual angle, and in optics, it is ...

of this star has been measured using the CHARA array to 2% accuracy. After correcting for limb darkening, this gives the stellar radius as 13.4 times the

radius of the Sun Solar radius is a unit of distance used to express the size of stars in astronomy relative to the Sun. The solar radius is usually defined as the radius to the layer in the Sun's photosphere where the optical depth equals 2/3: :1\,R_ = 6.957\t ...

. The star is radiating about 85 times the luminosity of the Sun and has 2.7 times the Sun's mass. With its large size and low

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 , it takes about 253 days to complete a rotation.

References

{{Authority control G-type giants Horizontal-branch stars Hyades (star cluster) Taurus (constellation) Prima Hyadum Tauri, Gamma Durchmusterung objects Tauri, 054 027371 020205

1346 Year 1346 ( MCCCXLVI) was a common year starting on Sunday of the Julian calendar. It was a year in the 14th century, in the midst of a period known in European history as the Late Middle Ages. In Asia that year, the Black Death came to the troop ...