Delta Sagittarii (δ Sagittarii, abbreviated Delta Sgr, δ Sgr), formally named Kaus Media , is a star in the southern

zodiac The zodiac is a belt-shaped region of the sky that extends approximately 8° north and south celestial latitude of the ecliptic – the apparent path of the Sun across the celestial sphere over the course of the year. Within this zodiac ...

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 ...

Sagittarius Sagittarius ( ) may refer to: *Sagittarius (constellation) *Sagittarius (astrology), a sign of the Zodiac * Sagittarius of Gap, a 6th century bishop *Sagittarius A*, the supermassive black hole at the center of the Milky Way galaxy Ships *'' S ...

. The

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 this star is +2.70, making it easily visible to the naked eye.

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 place the distance at roughly from 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 ...

Properties

Eggleton and Tokovinin (2008) list Delta Sagittarii as 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 consisting of an

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 ...

K-type

giant star A giant star has a substantially larger radius and luminosity than a main-sequence (or ''dwarf'') star of the same surface temperature. They lie above the main sequence (luminosity class V in the Yerkes spectral classification) on the Hertzsp ...

with 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 K3 III, and a

white dwarf A white dwarf is a Compact star, stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very density, dense: in an Earth sized volume, it packs a mass that is comparable to the Sun. No nuclear fusion takes place i ...

companion. The giant has an estimated mass three times that of the Sun, and is most likely fusing helium to carbon in its core. It is a weak

barium star Barium stars are spectral class G to K stars whose spectra indicate an overabundance of s-process elements by the presence of singly ionized barium, Ba II, at λ 455.4 nm. Barium stars also show enhanced spectral features of carbon, the b ...

, most likely having had its surface abundance of

s-process The slow neutron-capture process, or ''s''-process, is a series of nuclear reactions, reactions in nuclear astrophysics that occur in stars, particularly asymptotic giant branch stars. The ''s''-process is responsible for the creation (nucleosynt ...

elements enhanced through mass transfer from an orbiting companion, presumed to be a white dwarf. It has an estimated 3.21 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 is about 260million years old. Delta Sagittarii has three dim visual companions: * a 14th magnitude star at a separation of 26

arcsecond A minute of arc, arcminute (abbreviated as arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of a degree. Since one degree is of a turn, or complete rotation, one arcminute is of a tu ...

s, * a 15th magnitude star at a separation of 40 arcseconds, and * a 13th magnitude star at a separation of 58 arcseconds from the primary.

Nomenclature

''δ Sagittarii'' ( Latinised to ''Delta Sagittarii'') is the star's

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 ...

. It bore the traditional names ''Kaus Media'', ''Kaus Meridionalis'', and ''Media'', which derive from the ('bow') and ('middle'). In 2016, 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 ...

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's first bulletin of July 2016 included a table of the first two batches of names approved by the WGSN; which included ''Kaus Media'' for this star. 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 , meaning 'second of

Warida Warida or Al Warida is an asterism of the Arabs. In the star catalogue of Al Achsasi al Mouakket, four stars are mentioned as belonging to it: Gamma Sagittarii, Delta Sagittarii, Epsilon Sagittarii and Eta Sagittarii. The name is short for Arabic � ...

'. 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 ...

, ('

Winnowing Basket A winnowing basket or fan is a tool for winnowing grain from chaff while removing dirt and dust too. They have been used traditionally in a number of civilizations for centuries, and are still in use today in some countries. Use Unprocessed g ...

') refers to an asterism consisting of Delta Sagittarii, Gamma² Sagittarii,

Epsilon Sagittarii Epsilon Sagittarii ( Latinised from ε Sagittarii, abbreviated Epsilon Sgr, ε Sgr), formally named Kaus Australis , is a binary star system in the southern zodiac constellation of Sagittarius. The apparent visual magnitud ...

and

Eta Sagittarii Eta Sagittarii (Eta Sgr, η Sagittarii, η Sgr) is a binary star system in the southern zodiac constellation of Sagittarius. Based upon parallax measurements, it is located at a distance of from Earth. In India, where part ...

. 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 Delta Sagittarii itself is ('the Second Star of Winnowing Basket'). This star, together with Gamma Sagittarii, Epsilon Sagittarii,

Zeta Sagittarii Zeta Sagittarii (ζ Sagittarii, abbreviated Zeta Sgr, ζ Sgr) is a triple star system and the third-brightest star in the constellation of Sagittarius after Kaus Australis and Nunki. Based upon parallax measurements, i ...

Lambda Sagittarii Lambda Sagittarii ( Latinized from λ Sagittarii), formally named Kaus Borealis , is a star in the southern constellation of Sagittarius. The star marks the top of the Archer's bow. Properties With an apparent visual magnitude of ...

Sigma Sagittarii Sigma Sagittarii, Latinized from σ Sagittarii; formally named Nunki , is the second-brightest star in the constellation of Sagittarius. It is a binary star system, viewed as a single star of combined apparent magnitude +2.05, abou ...

Tau Sagittarii Tau Sagittarii (Tau Sgr, τ Sagittarii, τ Sgr) is a star in the southern zodiac constellation of Sagittarius. Description With an apparent visual magnitude of +3.3, this is one of the brighter members of the constellatio ...

and

Phi Sagittarii Phi Sagittarii, Latinized from φ Sagittarii, is a binary star in the southern constellation of Sagittarius. With an apparent visual magnitude of 3.17, it is the ninth-brightest star in the constellation and is readily visible to ...

, comprises the

Teapot A teapot is a vessel used for steeping tea leaves or a herbal mix in boiling or near-boiling water and serving the resulting infusion called tea; usually put in a teacup. It is one of the core components of teaware. Teapots usually have an ...

asterism. In Hindu astrology, this star is also called .

Notes

References

* {{DEFAULTSORT:Delta Sagittarii K-type giants Barium stars Binary stars Sagittarii, Delta Sagittarius (constellation) Kaus Media Sagittarii, 19 089931 6859 168454 Durchmusterung objects White dwarfs