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

star A star is an astronomical object comprising a luminous spheroid of plasma held together by its gravity. The nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night, but their immense distances from Earth make ...

at a distance of from the

Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared rad ...

in the southern constellation of

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

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 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. T ...

. It bore the traditional name ''Algorab'' derived from

Arabic Arabic (, ' ; , ' or ) is a Semitic language spoken primarily across the Arab world.Semitic languages: an international handbook / edited by Stefan Weninger; in collaboration with Geoffrey Khan, Michael P. Streck, Janet C. E.Watson; Walte ...

''الغراب'' ''al-ghuraab'', meaning 'the crow'). In 2016, 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, outreach ...

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 List of proper names of stars, proper names for stars for the international astronomical community. It operates under ...

(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 cart driven by a charioteer, usually using horses to provide rapid motive power. The oldest known chariots have been found in burials of the Sintashta culture in modern-day Chelyabinsk Oblast, Russia, dated to c. 2000&nb ...

'', refers to an asterism consisting of Delta Corvi, Gamma Corvi, Epsilon Corvi and Beta Corvi. Consequently, Delta Corvi itself is known as (, en, the Third Star of Chariot).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 standard unit of mass in astronomy, equal to approximately . It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxies and black holes. It is approximately equal to the mass of ...

, 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 nomi ...

. 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 An A-type main-sequence star (A V) or A dwarf star is a main-sequence (hydrogen-burning) star of spectral type A and luminosity class V (five). These stars have spectra defined by strong hydrogen Balmer absorption lines. They measure between 1 ...

. The

spectrum A spectrum (plural ''spectra'' or ''spectrums'') is a condition that is not limited to a specific set of values but can vary, without gaps, across a continuum. The word was first used scientifically in optics to describe the rainbow of color ...

matches a

stellar classification 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 t ...

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 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 ...

. 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 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 Sir James South FRS FRSE PRAS FLS LLD (October 1785 – 19 October 1867) was a British astronomer. He was a joint founder of the Astronomical Society of London, and it was under his name, as President of the Society in 1831, that a peti ...

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, experimental photographer who invented the blueprint and did botanic ...

. 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 \theta (also known as angular separation, apparent distance, or apparent separation) is the angle between the two sightlines, or between two point objects as viewed from an observer. Angular distance appears in mathematics (in pa ...

of 24.2

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

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 north celestial pole (NCP), turning positive into the ...

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 celestial objects and phenomena that originate outsi ...

, 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) is a

United States Navy The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage ...

ship named after the star.

References

{{Stars of Corvus Corvus (constellation) Corvi, Delta A-type subgiants

Algorab Delta Corvi (δ Corvi, abbreviated Delta Crv, δ Crv), also named Algorab , is a third Apparent magnitude, magnitude star at a distance of from the Sun in the Southern celestial hemisphere, southern constellation of Corvus (constellation), ...

Corvi, 07 060965 4757 108767 Durchmusterung objects