Gamma Boötis 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 ...

Boötes Boötes ( ) is a constellation in the northern sky, located between 0° and +60° declination, and 13 and 16 hours of right ascension on the celestial sphere. The name comes from , which comes from 'herder, herdsman' or 'plowman' (literally, 'o ...

the herdsman, forming the left shoulder of this asterism. Its name is a

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 ...

that is Latinised from γ Boötis, and abbreviated Gamma Boo or γ Boo. The primary component has the proper name Seginus, pronounced , the traditional name of the Gamma Bootis system. It has a white hue and is visible to the

naked eye Naked eye, also called bare eye or unaided eye, is the practice of engaging in visual perception unaided by a magnification, magnifying, Optical telescope#Light-gathering power, light-collecting optical instrument, such as a telescope or microsc ...

with a typical

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 +3.03. Based on

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 86

light-year A light-year, alternatively spelled light year (ly or lyr), is a unit of length used to express astronomical distances and is equal to exactly , which is approximately 9.46 trillion km or 5.88 trillion mi. As defined by the International Astr ...

s, but is drifting closer to the

Sun The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...

with a

radial velocity The radial velocity or line-of-sight velocity of a target with respect to an observer is the rate of change of the vector displacement between the two points. It is formulated as the vector projection of the target-observer relative velocity ...

of −32 km/s.

Properties

The double nature of this system was discovered by American astronomer S. W. Burnham in 1878, and has the discovery code BU 616. The system is resolved into a pair separated by with a brightness difference of 9.7 magnitudes. The brighter primary is itself a close pair separated by , as discovered by B. L. Morgan and associates in 1975. The primary or 'A' component of this

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 ...

system is designated WDS J14321+3818 ('B' is the star UCAC2 45176266) in 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 January 2024) 1 ...

. Parallax measurements for component B give a distance of approximately . Gamma Boötis' two components are themselves designated WDS J14321+3818Aa (Seginus) and Ab. GammaBooLightCurve

The

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 Gamma Boötis is A7IV+(n), matching an

A-type star A type or type A may refer to: Science * A-type asteroid, a type of relatively uncommon inner-belt asteroids * A type blood, a type in the ABO blood group system * A-type inclusion, a type of cell inclusion * A-type potassium channel, a type of ...

with somewhat "nebulous" lines due to rapid rotation. It was found to be a short-period

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

in 1914 by German astronomers P. Guthnick and R. Prager. Non-radial pulsations were detected in 1992 by Edward J. Kennelly and colleagues. It is a Delta Scuti-type

with a period of that varies from magnitude +3.02 down to +3.07. This dominant mode is 21.28 cycles per day with an amplitude of 0.05 in magnitude. Additional pulsations occur at 18.09, 12.02, 11.70 and 5.06 cycles per day. These types of stars are usually on the

main sequence In astronomy, the main sequence is a classification of stars which appear on plots of stellar color index, color versus absolute magnitude, brightness as a continuous and distinctive band. Stars on this band are known as main-sequence stars or d ...

or slightly

evolved Evolution is the change in the heritable Phenotypic trait, characteristics of biological populations over successive generations. It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, re ...

. The primary is around one billion years old with 2.1 times the

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

and 4.65 times the

Sun's radius Solar radius is a unit of distance used to express the size of objects 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\ti ...

. Measurements of the

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 ...

range from 115 to 145 km/s, suggesting a high rate of spin. On average, the star is radiating 33.4 times the

luminosity of the Sun 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 s ...

from its

photosphere The photosphere is a star's outer shell from which light is radiated. It extends into a star's surface until the plasma becomes opaque, equivalent to an optical depth of approximately , or equivalently, a depth from which 50% of light will esc ...

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 . The system displays a statistically significant

infrared excess An infrared excess is a measurement of an astronomical source, typically a star, that in their spectral energy distribution has a greater measured infrared flux than expected by assuming the star is a blackbody radiator. Infrared excesses are of ...

due to a

circumstellar disk A Circumstellar disc (or circumstellar disk) is a torus, pancake or ring-shaped accretion disk of matter composed of gas, dust, planetesimals, asteroids, or collision fragments in orbit around a star. Around the youngest stars, they are the res ...

. A model fit to the data indicates this material has a mean temperature of 85 K and is orbiting at a distance of .

Nomenclature

''γ Boötis'' ( Latinised to ''Gamma Boötis'') is the binary's

. WDS J14321+3818 is the wider system's designation in the

. The designations of the two constituents as WDS J14321+3818A and B, and those of A's components—WDS J14321+3818Aa and Ab—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. It may sometimes be used to refer to a single star. A large group of stars bound by gravitation is generally called a ''st ...

s, and adopted by the

International Astronomical Union The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...

(IAU). Gamma Boötis bore the traditional name ''Ceginus'' (later ''Seginus''), from ''cheguius'' or ''theguius'', apparently Latin mistranscriptions of an

Arabic Arabic (, , or , ) is a Central Semitic languages, Central Semitic language of the Afroasiatic languages, Afroasiatic language family spoken primarily in the Arab world. The International Organization for Standardization (ISO) assigns lang ...

rendering of Greek ''Boötes''. Two possibilities have been suggested: from Arabic بوطس ''bwṭs'', in one of the manuscripts of the ''

Almagest The ''Almagest'' ( ) is a 2nd-century Greek mathematics, mathematical and Greek astronomy, astronomical treatise on the apparent motions of the stars and planetary paths, written by Ptolemy, Claudius Ptolemy ( ) in Koine Greek. One of the most i ...

'', with undotted ب ''b'' mistaken for an undotted ث ''th'', و ''w'' taken as ''w'' and spelled 'gu', and ط ''ṭ'' completely misread, or from Arabic بؤوتس ''bwʾwts'', with undotted ب ''b'' mistaken for an undotted ث ''th'', ؤ ''w-hamza'' mistaken for غ ''ġ'', و ''w'' read as ''u'', and undotted ن ''n'' misread as an undotted ى ''y'' and transcribed ''i''—that is, as ''th-g-u-i-s'' with unwritten vowels (and the Latin grammatical ending ''-us'') filled in for ''theguius''. 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 catalogue 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 ''Seginus'' for WDS J14321+3818Aa on 21 August 2016 and it is now so included in the List of IAU-approved Star Names. Gamma Boötis was listed as ''Haris'' in Bečvář, apparently derived from the Arabic name of the constellation of Boötes, ''Al-Haris Al-Sama'' meaning "the guard of the north". In the catalogue of stars in the ''Calendarium'' of

Al Achsasi al Mouakket Muḥammad al Achsasi al Mouakket () was a 17th century Egyptian astronomer whose and catalogue of stars, ("''Pearls of brilliance upon the solar operations''"), was written in Cairo in about 1650. Al-Achsasi was a shaykh, a learned elder, of th ...

, this star was designated ''Menkib al Aoua al Aisr'' (منكب العواء الأيسر – ''mankibu lʿawwaaʾi lʾaysar''), which was translated into

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

as ''Humerus Sinister Latratoris'', meaning 'the left shoulder of barker'. In

Chinese astronomy Astronomy in China has a long history stretching from the Shang dynasty, being refined over a period of more than 3,000 years. The Ancient China, ancient Chinese people have identified stars from 1300 BCE, as Chinese star names later categori ...

, Gamma Boötis is called 招搖,

Pinyin Hanyu Pinyin, or simply pinyin, officially the Chinese Phonetic Alphabet, is the most common romanization system for Standard Chinese. ''Hanyu'' () literally means 'Han Chinese, Han language'—that is, the Chinese language—while ''pinyin' ...

: Zhāoyáo, meaning ''Twinkling Indicator'', because this star is marking itself and standing alone in ''Twinkling Indicator'' asterism,

Root In vascular plants, the roots are the plant organ, organs of a plant that are modified to provide anchorage for the plant and take in water and nutrients into the plant body, which allows plants to grow taller and faster. They are most often bel ...

mansion (see:

Chinese constellation Traditional Chinese astronomy has a system of dividing the celestial sphere into asterisms or constellations, known as "officials" ( Chinese ''xīng guān''). The Chinese asterisms are generally smaller than the constellations of Hellenisti ...

). 招搖 (Zhāoyáo), westernized into ''Chaou Yaou'', but the name ''Chaou Yaou'' was designated for Beta Boötis (Nekkar) by R.H. Allen and the meaning is "to beckon, excite, or move."

Namesake

USS ''Seginus'' (AK-133) was a U.S. Navy ''Crater''-class cargo ship named after the star.

References

External links

HR 5435

CCDM J14321+3818
{{DEFAULTSORT:Gamma Bootis A-type subgiants Delta Scuti variables Circumstellar disks Binary stars Boötes Bootis, Gamma BD+38 2565 5435 Bootis, 27 127762 071075 Seginus