Delta Corvi (δ Corvi, abbreviated Delta Crv, δ Crv), also named Algorab , is a third

magnitude Magnitude may refer to: Mathematics *Euclidean vector, a quantity defined by both its magnitude and its direction *Magnitude (mathematics), the relative size of an object *Norm (mathematics), a term for the size or length of a vector *Order of ...

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 ...

at a distance of 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 ...

in the southern

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 ...

Corvus ''Corvus'' is a widely distributed genus of passerine birds ranging from medium-sized to large-sized in the family Corvidae. It includes species commonly known as crows, ravens, and rooks. The species commonly encountered in Europe are the car ...

Nomenclature

''δ Corvi'' ( Latinised to ''Delta Corvi'') 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 name ''Algorab'' derived from

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 ...

''الغراب'' ''al-ghuraab'', meaning 'the crow'. 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 ''Algorab'' for this star. In Chinese, (), meaning ''

Chariot A chariot is a type of vehicle similar to a cart, driven by a charioteer, usually using horses to provide rapid Propulsion, motive power. The oldest known chariots have been found in burials of the Sintashta culture in modern-day Chelyabinsk O ...

'', refers to an asterism consisting of Delta Corvi,

Gamma Corvi Gamma Corvi (γ Corvi, abbreviated Gamma Crv, γ Crv) is a binary star and the brightest star in the southern constellation of Corvus, having an apparent visual magnitude of 2.59. The system's two components are designated Gamma Corvi A (o ...

, Epsilon Corvi and

Beta Corvi Beta Corvi or β Corvi, officially named Kraz (), is the second-brightest star in the southern constellation of Corvus with an apparent visual magnitude of 2.647. Based on parallax measurements obtained during the Hipparcos miss ...

. Consequently, Delta Corvi itself is known as (, ).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.

Stellar properties

Delta Corvi has more than 2.7 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 ...

, which is causing it to radiate a much higher energy output—roughly 69 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 s ...

. The

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 outer atmosphere is , giving it the white hue of 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 ...

. The

spectrum A spectrum (: spectra or spectrums) is a set of related ideas, objects, or properties whose features overlap such that they blend to form a continuum. The word ''spectrum'' was first used scientifically in optics to describe the rainbow of co ...

matches 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 . However, it is more luminous—65 to 70 times that of the Sun—than it would be if it were 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 ...

. Hence it is either a

subgiant A subgiant is a star that is brighter than a normal main-sequence star of the same spectral class, but not as bright as giant stars. The term subgiant is applied both to a particular spectral luminosity class and to a stage in the evolution ...

star around 260 million years old that has nearly exhausted the supply of hydrogen at its core and is in the process of

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

away from the main sequence of stars like the Sun, or a pre-main-sequence star around 3.2 million years old that has not completely condensed and settled on the main sequence. In 1823, Delta Corvi was found to be a wide

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 ...

by British astronomers James South and

John Herschel Sir John Frederick William Herschel, 1st Baronet (; 7 March 1792 – 11 May 1871) was an English polymath active as a mathematician, astronomer, chemist, inventor and experimental photographer who invented the blueprint and did botanical work. ...

. Since that time, the position of the two stars with respect to each other has not changed. The magnitude 9.3 companion, HR 4757 B, with a classification of K2Ve, is at an

angular separation Angular distance or angular separation is the measure of the angle between the orientation of two straight lines, rays, or vectors in three-dimensional space, or the central angle subtended by the radii through two points on a sphere. When t ...

of 24.2

arcseconds 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 ...

along a

position angle In astronomy, position angle (usually abbreviated PA) is the convention for measuring angles on the sky. The International Astronomical Union defines it as the angle measured relative to the Celestial pole, north celestial pole (NCP), turning pos ...

of 214°. Although the two stars share a

common proper motion This glossary of astronomy is a list of definitions of terms and concepts relevant to astronomy and cosmology, their sub-disciplines, and related fields. Astronomy is concerned with the study of astronomical object, celestial objects and phenomena ...

, the significant differences in their estimated ages suggests that they may not be physically connected. A 2006 study found that Delta Corvi displayed no excess infrared emission that would otherwise suggest the presence of circumstellar matter; however, warm interstellar dust was detected in a 2014 study.

In culture

USS ''Algorab'' (AKA-8) was a

United States Navy The United States Navy (USN) is the naval warfare, maritime military branch, service branch of the United States Department of Defense. It is the world's most powerful navy with the largest Displacement (ship), displacement, at 4.5 millio ...

ship named after the star. Algorab is one of the Behenian fixed stars.

Notes

References

{{Stars of Corvus Corvus (constellation) Corvi, Delta A-type subgiants Algorab Corvi, 07 060965 4757 108767 Durchmusterung objects