Cor Caroli 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 ...

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 ...

Canes Venatici Canes Venatici ( ) is one of the 88 constellations designated by the International Astronomical Union (IAU). It is a small northern constellation that was created by Johannes Hevelius in the 17th century. Its name is Latin for 'hunting dogs', and ...

. It is the brightest star in the constellation, lying at the third magnitude. 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 ...

uses the name "Cor Caroli" specifically for the brighter star of the binary. The system has the

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 ...

Alpha Canum Venaticorum or α Canum Venaticorum.

Nomenclature

''α Canum Venaticorum'', Latinised to ''Alpha Canum Venaticorum'', is the system's

. The brighter of the two

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 ...

s is designated ''α² Canum Venaticorum'', the fainter ''α¹ Canum Venaticorum''. In the

western world The Western world, also known as the West, primarily refers to various nations and state (polity), states in Western Europe, Northern America, and Australasia; with some debate as to whether those in Eastern Europe and Latin America also const ...

Alpha Canum Venaticorum had no name until the 17th century, when it was named ''Cor Caroli'', which means "Charles's Heart". There has been some uncertainty whether it was named in honour of King

Charles I of England Charles I (19 November 1600 – 30 January 1649) was King of Kingdom of England, England, Kingdom of Scotland, Scotland, and Kingdom of Ireland, Ireland from 27 March 1625 until Execution of Charles I, his execution in 1649. Charles was born ...

, who was executed in 1649 during the

English Civil War The English Civil War or Great Rebellion was a series of civil wars and political machinations between Cavaliers, Royalists and Roundhead, Parliamentarians in the Kingdom of England from 1642 to 1651. Part of the wider 1639 to 1653 Wars of th ...

, or of his son, Charles II, who

restored ''Restored'' is the fourth studio album by American contemporary Christian musician Jeremy Camp. It was released on November 16, 2004, by BEC Recordings. Track listing Standard release Enhanced edition Deluxe gold edition Standard Aus ...

the English monarchy to the throne in 1660. The name was coined in 1660 by Sir

Charles Scarborough Sir Charles Scarborough or Scarburgh Member of Parliament, MP Fellow of the Royal Society, FRS Fellow of the Royal College of Physicians, FRCP (29 December 1615 – 26 February 1694) was an English physician and mathematician.Robert L. Martensen ...

, physician to Charles II, who claimed the star seemed to shine exceptionally brightly on the night of Charles II's return to England. In ''Star Names'', R.H. Allen claimed that Scarborough suggested the name to

Edmond Halley Edmond (or Edmund) Halley (; – ) was an English astronomer, mathematician and physicist. He was the second Astronomer Royal in Britain, succeeding John Flamsteed in 1720. From an observatory he constructed on Saint Helena in 1676–77, Hal ...

and intended it to refer to Charles II. However, Robert Burnham Jr. notes that "the attribution of the name to Halley appears in a report published by J. E. Bode at Berlin in 1801, but seems to have no other verification". In ''Star Tales'',

Ian Ridpath Ian William Ridpath (born 1 May 1947, in Ilford, Essex) is an English science writer and broadcaster best known as a popularizer of astronomy and a biographer of constellation history. As a UFO sceptic, he investigated and explained the Rendle ...

points out that the name's first appearance on a star map was in the 1673 chart of Francis Lamb, who labelled it ''Cor Caroli Regis Martyris'' ('the heart of Charles the martyred king'), clearly indicating that it was seen as referring to Charles I. In 2016, the

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 ''Cor Caroli'' for the star α² Canum Venaticorum. In

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 ...

, (), meaning '' Imperial Guards'', refers to an asterism consisting of α Canum Venaticorum, 10 Canum Venaticorum,

Beta Canum Venaticorum Beta Canum Venaticorum (β Canum Venaticorum, abbreviated Beta CVn, β CVn), also named Chara , is the second-brightest star in the northern constellation of Canes Venatici. It is a nearby solar-type star, about distant based on its stell ...

, 6 Canum Venaticorum, 2 Canum Venaticorum and

67 Ursae Majoris This is the list of notable stars in the constellation Ursa Major, sorted by decreasing brightness. See also *List of stars by constellation References * * * * {{Lists of stars by constellation *List Ursa Major Ursa Major, also known ...

. 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 Alpha Canum Venaticorum itself is (, ). From this Chinese name, the name ''Chang Chen'' was derived.

Stellar properties

Alpha Canum Venaticorum is a

with a combined

apparent magnitude Apparent magnitude () is a measure of the Irradiance, 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 (astronomy), ...

of 2.81. The two stars are 19.6

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 ...

apart in the sky and are easily resolved in small telescopes. The system lies approximately 110

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 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 ...

. It marks the northern vertex of the asterism known as the

Great Diamond The Great Diamond, also called the Diamond of Virgo, is an asterism that can be seen during spring evenings in the Northern Hemisphere. It is composed of the following stars: *Cor Caroli (α CVn), in Canes Venatici * Denebola (β Leo), the tai ...

or the Diamond of Virgo.

α² Canum Venaticorum

α² Canum Venaticorum has a

spectral type 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 ...

of A0, and 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 ...

which varies between 2.84 and 2.98, with a period of 5.47 days. It is a

chemically peculiar star In astrophysics, chemically peculiar stars (CP stars) are stars with distinctly unusual Metallicity, metal abundances, at least in their surface layers. Classification Chemically peculiar stars are common among hot main-sequence (hydrogen-burning) ...

with a strong magnetic field, about 5,000 times as strong as the Earth's, and is also classified as an Ap/Bp star. Its atmosphere has overabundances of some elements, such as

silicon Silicon is a chemical element; it has symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic lustre, and is a tetravalent metalloid (sometimes considered a non-metal) and semiconductor. It is a membe ...

, mercury and

europium Europium is a chemical element; it has symbol Eu and atomic number 63. It is a silvery-white metal of the lanthanide series that reacts readily with air to form a dark oxide coating. Europium is the most chemically reactive, least dense, and soft ...

. This is thought to be due to some elements sinking down into the star under the force of gravity while others are elevated by radiation pressure. This star is the prototype of a class of

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 ...

s, the so-called α² Canum Venaticorum variables. The strong

magnetic field A magnetic field (sometimes called B-field) is a physical field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular ...

of these stars is believed to produce

starspot Starspots are stellar phenomena, so-named by analogy with sunspots. Spots as small as sunspots have not been detected on other stars, as they would cause undetectably small fluctuations in brightness. The commonly observed starspots are in gene ...

s of enormous extent. Due to these starspots the brightness of α² Canum Venaticorum stars varies considerably during their rotation.

α¹ Canum Venaticorum

α¹ Canum Venaticorum is an

F-type main-sequence star An F-type main-sequence star (F V) is a main-sequence, hydrogen-fusing star of spectral type F and luminosity class V. These stars have from 1.0 to 1.4 times the mass of the Sun and surface temperatures between 6,000 and 7,600 K.Tables ...

. It is considerably fainter than its companion and has an apparent visual magnitude of approximately 5.60.

Namesakes

''Cor Caroli'' was a

U.S. Navy The United States Navy (USN) is the maritime service branch of the United States Department of Defense. It is the world's most powerful navy with the largest displacement, at 4.5 million tons in 2021. It has the world's largest aircraft ...

''Crater''-class cargo ship named after the star.

References

{{DEFAULTSORT:Cor Caroli Canes Venatici Canum Venaticorum, Alpha Canum Venaticorum, 12 112412 063121 A-type main-sequence stars F-type main-sequence stars Binary stars Alpha2 Canum Venaticorum variables Stars with proper names Durchmusterung objects 4914 TIC objects