Epsilon Scorpii (ε Scorpii, abbreviated Eps Sco, ε Sco), formally named Larawag , is a

star A star is a luminous spheroid of plasma (physics), plasma held together by Self-gravitation, self-gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night sk ...

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 ...

Scorpius Scorpius is a zodiac constellation located in the Southern celestial hemisphere, where it sits near the center of the Milky Way, between Libra to the west and Sagittarius to the east. Scorpius is an ancient constellation whose recognition pred ...

. It 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 +2.3, making it the fifth-brightest member of the constellation.

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 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 and distances of ...

mission provide an estimated distance to this star of around 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 ...

. Epsilon Scorpii has 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 K1 III, which indicates it has exhausted the supply of hydrogen at its core and

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 ...

into a

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 ...

. The

interferometry Interferometry is a technique which uses the ''interference (wave propagation), interference'' of Superposition principle, superimposed waves to extract information. Interferometry typically uses electromagnetic waves and is an important inves ...

-measured

angular diameter The angular diameter, angular size, apparent diameter, or apparent size is an angular separation (in units of angle) describing how large a sphere or circle appears from a given point of view. In the vision sciences, it is called the ''visual an ...

of this star, after correcting for

limb darkening Limb darkening is an optical effect seen in stars (including the Sun) and planets, where the central part of the disk appears brighter than the edge, or '' limb''. Its understanding offered early solar astronomers an opportunity to construct mode ...

, is , which, at its estimated distance, equates to a physical radius of nearly 12 times the

radius of the Sun 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 ...

. Presently it is generating energy through the

nuclear fusion Nuclear fusion is a nuclear reaction, reaction in which two or more atomic nuclei combine to form a larger nuclei, nuclei/neutrons, neutron by-products. The difference in mass between the reactants and products is manifested as either the rele ...

of helium at its core, which, considering the star's composition, places it along an evolutionary branch termed the

red clump The red clump is a clustering of red giants in the Hertzsprung–Russell diagram at around 5,000 K and absolute magnitude (MV) +0.5, slightly hotter than most red-giant-branch stars of the same luminosity. It is visible as a denser region of ...

. The star's outer atmosphere has 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 4,560 K, giving it the orange hue of a cool

K-type star 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 ...

. ε Scorpii is classified as a suspected

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 ...

, although a study of

photometry showed a variation of no more than 0.01–0.02 magnitudes. It is an X-ray source with a luminosity of .

Nomenclature

''ε Scorpii'' ( Latinised to ''Epsilon Scorpii'') 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 ...

. The star bore the traditional name ''Larawag'' in the culture of the

Wardaman people The Wardaman people are a small group of Aboriginal Australians living about South-West of Katherine, on Menngen Aboriginal Land Trust in the Northern Territory of Australia. Language Wardaman is a non- Pama-Nyungan language. Though close to ...

of the

Northern territory The Northern Territory (abbreviated as NT; known formally as the Northern Territory of Australia and informally as the Territory) is an states and territories of Australia, Australian internal territory in the central and central-northern regi ...

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

, meaning ''clear sighting''. 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 name ''Larawag'' for Epsilon Scorpii on 19 November 2017 and it is now so included in the List of IAU-approved Star Names.

Patrick Moore Sir Patrick Alfred Caldwell-Moore (; 4 March 1923 – 9 December 2012) was an English amateur astronomer who attained prominence in that field as a writer, researcher, radio commentator and television presenter. Moore's early interest in astro ...

introduced the name ''Wei'' as

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 this star. However, this seems to be a misreading, as

Chinese 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-ethnic ...

(, English ''

Tail The tail is the elongated section at the rear end of a bilaterian animal's body; in general, the term refers to a distinct, flexible appendage extending backwards from the midline of the torso. In vertebrate animals that evolution, evolved to los ...

'') refers to an asterism (i.e.

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 ...

) consisting of Epsilon Scorpii,

Mu¹ Scorpii Mu1 Scorpii (μ1 Scorpii, abbreviated Mu1 Sco, μ1 Sco) is a binary star system in the southern zodiac constellation of Scorpius. The combined apparent visual magnitude of the pair is about magnitude 3, making it one of the brighter m ...

Zeta¹ Scorpii Zeta1 Scorpii (Zeta1 Sco, ζ1 Scorpii, ζ1 Sco) is a B-type hypergiant star in the constellation of Scorpius. It has an apparent visual magnitude which varies between 4.66 and 4.86. It is a member of the Scorpiu ...

and

Zeta² Scorpii Zeta2 Scorpii (Zeta2 Sco, ζ2 Scorpii, ζ2 Sco) is a star in the constellation of Scorpius. With an apparent visual magnitude variying s between 3.59 and 3.65, this star is visible to the naked eye. Parallax measureme ...

Eta Scorpii Eta Scorpii, Latinized from η Scorpii, is a star in the southern zodiac constellation of Scorpius. With an apparent visual magnitude of 3.33, this is one of the brighter members of the Scorpius and is the furthest south of the constel ...

Theta Scorpii Theta Scorpii (θ Scorpii, abbreviated Theta Sco, θ Sco) is a binary star in the southern zodiac constellation of Scorpius. The apparent visual magnitude of this star is +1.87, making it readily visible to the naked eye and one of the b ...

, Iota² Scorpii and Iota¹ Scorpii,

Kappa Scorpii Kappa Scorpii, Latinisation of names, Latinized from κ Scorpii, is a binary star system in the southern constellation of Scorpius. With an apparent visual magnitude of 2.4, this star system is readily visible to the naked eye. Parallax ...

Lambda Scorpii Lambda Scorpii is a triple star system and the second-brightest object in the constellation of Scorpius. It is formally named Shaula; ''Lambda Scorpii'' is its Bayer designation, which is Latinised from λ Scorpii and abbreviated Lam ...

and

Upsilon Scorpii Upsilon Scorpii (υ Scorpii, abbreviated Upsilon Sco, υ Sco), formally named Lesath , is a star located in the "stinger" of the southern zodiac constellation of Scorpius, the scorpion. Based on parallax measurements obtained during the H ...

. Consequently, the name for Epsilon Scorpii itself is (), which means "the Second Star of Tail".

In culture

Epsilon Scorpii appears on the

flag of Brazil The national flag of Brazil is a blue disc depicting a starry sky (which includes the Crux, Southern Cross) spanned by a curved band inscribed with the List of national mottos, national motto ('Order and Progress'), within a yellow rhombus, on ...

, symbolising the state of

Ceará Ceará (, ) is one of the 26 states of Brazil, located in the Northeast Region, Brazil, northeastern part of the country, on the Atlantic Ocean, Atlantic coast. It is the List of Brazilian states by population, eighth-largest Brazilian State by ...

References

{{Stars of Scorpius K-type giants Horizontal-branch stars Suspected variables Scorpius Larawag Scorpii, Epsilon Durchmusterung objects Scorpii, 26 9579 151680 082396 6241