Cor Caroli is a

binary star A binary star 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 using a telescope as separate stars, in ...

designated Alpha Canum Venaticorum or α Canum Venaticorum. 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 ...

uses the name "Cor Caroli" specifically for the brighter star of the binary. Alpha Canum Venaticorum is the brightest point of light in the northern constellation of

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 ...

Nomenclature

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

. The brighter of the two

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 ...

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 the various nations and states in the regions of Europe, North America, and Oceania.

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 England, Scotland, and Ireland from 27 March 1625 until his execution in 1649. He was born into the House of Stuart as the second son of King James VI of Scotland, but after ...

, who was executed in 1649 during the

English Civil War The English Civil War (1642–1651) was a series of civil wars and political machinations between Parliamentarians ("Roundheads") and Royalists led by Charles I ("Cavaliers"), mainly over the manner of Kingdom of England, England's governanc ...

, or of his son, Charles II, who

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

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

Charles Scarborough Sir Charles Scarborough or Scarburgh MP FRS FRCP (29 December 1615 – 26 February 1694) was an English physician and mathematician.Robert L. Martensen, "Scarburgh, Sir Charles (1615–1694)", ''Oxford Dictionary of National Biography'' (Oxfor ...

, 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 Rendl ...

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 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 ''Cor Caroli'' for the star α² Canum Venaticorum. In Chinese, (), meaning ''

Imperial Guards An imperial guard or palace guard is a special group of troops (or a member thereof) of an empire, typically closely associated directly with the Emperor or Empress. Usually these troops embody a more elite status than other imperial forces, in ...

'', refers to an asterism consisting of α Canum Venaticorum, 10 Canum Venaticorum, Beta Canum Venaticorum,

6 Canum Venaticorum 6 Canum Venaticorum is a single star in the northern constellation Canes Venatici, located 246 light years from the Sun. It is visible to the naked eye as a faint yellow-hued star with an apparent visual magnitude of +5.01. The star ...

, 2 Canum Venaticorum and 67 Ursae Majoris. Consequently, the

Chinese name Chinese names or Chinese personal names are names used by individuals from Greater China and other parts of the Chinese-speaking world throughout East and Southeast Asia (ESEA). In addition, many names used in Japan, Korea and Vietnam are oft ...

for Alpha Canum Venaticorum itself is (, en, the First Star of Imperial Guards). 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 brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's li ...

of 2.81. The two stars are 19.6

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 ...

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, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 101 ...

s 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 ...

. It marks the northern vertex of the asterism known as the Great Diamond 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 th ...

of A0, and has an

apparent visual magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's lig ...

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 metal abundances, at least in their surface layers. Classification Chemically peculiar stars are common among hot main-sequence (hydrogen-burning) stars. Thes ...

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 with the symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic ...

, mercury and

europium Europium is a chemical element with the symbol Eu and atomic number 63. Europium is the most reactive lanthanide by far, having to be stored under an inert fluid to protect it from atmospheric oxygen or moisture. Europium is also the softest lanth ...

. 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 with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are classified as e ...

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

magnetic field A magnetic field is a vector 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 to its own velocity and t ...

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 gen ...

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 VI ...

. 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 ''Crater''-class cargo ship named after the star. The star is also named Naomie. Received this name on June 7th 2013.

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