Cor Caroli

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Binary star in the constellation of Canes Venatici

title: "Cor Caroli" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["canes-venatici", "bayer-objects", "flamsteed-objects", "henry-draper-catalogue-objects", "hipparcos-objects", "a-type-main-sequence-stars", "f-type-main-sequence-stars", "binary-stars", "alpha2-canum-venaticorum-variables", "stars-with-proper-names", "durchmusterung-objects", "bright-star-catalogue-objects", "lucidae"] description: "Binary star in the constellation of Canes Venatici" topic_path: "science/astronomy" source: "https://en.wikipedia.org/wiki/Cor_Caroli" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Binary star in the constellation of Canes Venatici ::

| name = α Canum Venaticorum | image = | image=Canes Venatici IAU.svg | float=center | width=240 | position=right | mark=Red circle.svg | mark_width=10 | mark_link=α CVn | x%=51.5 | y%=49.3 | caption = The location of α Canum Venaticorum (circled) | epoch = J2000.0 | equinox = J2000.0 (ICRS) | constell = Canes Venatici | component1 = α2 CVn | ra1 = | dec1 = | appmag_v1=2.84 to 2.98 | component2 = α1 CVn | ra2 = | dec2 = | appmag_v2=5.60 | component = α2 CVn | class = A0pSiEuHg | b-v = −0.12 | u-b = −0.32 | variable = α2 CVn | component2 = α1 CVn | class2 = F2V | b-v2 = +0.34 | u-b2 = −0.03 | component1 = α2 CVn | radial_v = | prop_mo_ra = −235.08 | prop_mo_dec = 53.54 | parallax = 32.7227 | p_error = 0.5844 | parallax_footnote = | absmag_v = | component2 = α1 CVn | radial_v2 = −0.60 ± 0.9 | prop_mo_ra2 = −232.86 | prop_mo_dec2 = 55.69 | parallax2 = 30.6121 | p_error2 = 0.0666 | parallax_footnote2 = | component1 = α2 CVn | temperature = | gravity = | luminosity = | radius = | mass = | age_myr = | rotational_velocity = | rotation = 5.46939 d | component2 = α1 CVn | gravity2 = | mass2 = | radius2 = 1.5 | temperature2 = 7,080 | rotational_velocity2 = 18 | names = | component1 = α2 CVn | names1 = | component2 = α1 CVn | names2 = | Simbad=alf02+CVn | sn=α2 CVn | Simbad2=alf01+CVn | sn2=α1 CVn

Cor Caroli is a binary star in the northern constellation of Canes Venatici. It is the brightest star in the constellation, lying at the third magnitude. The International Astronomical Union uses the name "Cor Caroli" specifically for the brighter star of the binary. The system has the Bayer designation Alpha Canum Venaticorum or α Canum Venaticorum.

Nomenclature

α Canum Venaticorum, Latinised to Alpha Canum Venaticorum, is the system's Bayer designation. The brighter of the two stars is designated α2 Canum Venaticorum, the fainter α1 Canum Venaticorum.

In the western world 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, who was executed in 1649 during the English Civil War, or of his son, Charles II, who restored the English monarchy to the throne in 1660. The name was coined in 1660 by Sir Charles Scarborough, 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 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 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 International Astronomical Union organized a Working Group on Star Names (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, 常陳 (Cháng Chén), meaning Imperial Guards, refers to an asterism consisting of α Canum Venaticorum, 10 Canum Venaticorum, Beta Canum Venaticorum, 6 Canum Venaticorum, 2 Canum Venaticorum and 67 Ursae Majoris. Consequently, the Chinese name for Alpha Canum Venaticorum itself is 常陳一 (Cháng Chén yī, ). From this Chinese name, the name Chang Chen was derived.

Stellar properties

::figure[src="https://upload.wikimedia.org/wikipedia/commons/8/84/Cor_Caroli_2011-03-01.jpeg" caption="Cor Caroli seen from northern England on March 1, 2011"] ::

Alpha Canum Venaticorum is a binary pair of stars that marks the northern vertex of the asterism known as the Great Diamond or the Diamond of Virgo. The system lies approximately 110 light-years from the Sun.

The two stars are separated by an estimated 650 - 670 Astronomical Units, and orbit a common center of mass with a period around 8,000 years. The pair have a combined apparent magnitude of 2.81. The two stars are 19.6 arcseconds apart in the sky and are easily resolved in small telescopes.

α2 Canum Venaticorum

::figure[src="https://upload.wikimedia.org/wikipedia/commons/a/a5/Alpha2CVnLightCurve.png" caption="TESS]]'' data"] ::

α2 Canum Venaticorum has a spectral type of A0, and has an apparent visual magnitude which varies between 2.84 and 2.98, with a period of 5.47 days. It is a chemically peculiar star 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, mercury and europium. 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 stars, the so-called α2 Canum Venaticorum variables. The strong magnetic field of these stars is believed to produce starspots 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. 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.

References

中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, .

| url=http://www.pas.rochester.edu/~emamajek/WGSN/WGSN_bulletin1.pdf | title=Bulletin of the IAU Working Group on Star Names, No. 1 | access-date=28 July 2016}}

| url=https://www.iau.org/science/scientific_bodies/working_groups/280/ | title=IAU Working Group on Star Names (WGSN)|access-date=22 May 2016}}

Ian Ridpath: "Star Tales", Canes Venatici. See also Deborah J. Warner, The Sky Explored: Celestial Cartography 1500-1800.

Cor Caroli {{webarchive | url=https://web.archive.org/web/20080704215122/http://www.astro.uiuc.edu/~kaler/sow/corcaroli.html | date=2008-07-04 }}, Stars, Jim Kaler. Accessed on line September 15, 2008.

| url=http://www.pas.rochester.edu/~emamajek/WGSN/IAU-CSN.txt | title=IAU Catalog of Star Names |access-date=28 July 2016}}

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| bibcode=2010A&A...513A..13K|doi=10.1051/0004-6361/200913860|arxiv=1002.0025 | title=Magnetic Doppler imaging of α2 Canum Venaticorum in all four Stokes parameters | journal=Astronomy and Astrophysics|volume=513|pages=A13|year=2010|last1=Kochukhov|first1=O. | last2=Wade|first2=G. A.|s2cid=53998003}}

| title=Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system | author=Gontcharov, G. A. | date=2006|journal=Astronomy Letters|volume=32|issue=11|pages=759–771 | bibcode=2006AstL...32..759G|doi=10.1134/S1063773706110065|arxiv=1606.08053|s2cid=119231169}}

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| author1=Mermilliod, J.-C. | title=Compilation of Eggen's UBV data, transformed to UBV (unpublished) | journal=Catalogue of Eggen's UBV Data | url=http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?1986EgUBV........0M&db_key=AST&nosetcookie=1|date=1986|bibcode= 1986EgUBV........0M}}

HR 4915, database entry, The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version), D. Hoffleit and W. H. Warren, Jr., CDS ID V/50. Accessed on line November 2, 2009.

| bibcode=2002yCat.2237....0D | title=VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system | journal=CDS/ADC Collection of Electronic Catalogues|volume=2237|author1=Ducati, J. R.|year=2002}}

alf 2 CVn, database entry, The combined table of GCVS Vols I-III and NL 67-78 with improved coordinates, General Catalogue of Variable Stars , Sternberg Astronomical Institute, Moscow, Russia. Accessed on line November 2, 2009.

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| title=Validation of the new Hipparcos reduction | url=http://www.aanda.org/index.php?option=com_article&access=bibcode&Itemid=129&bibcode=2007A%2526A...474..653VFUL | author=van Leeuwen, F.|display-authors=etal | journal=Astronomy and Astrophysics|volume=474|issue=2|pages=653–664|date=2007 | arxiv=0708.1752|bibcode=2007A&A...474..653V|doi=10.1051/0004-6361:20078357|s2cid = 18759600}}

References

  1. [https://ualr.edu/tv/2019/02/28/march-2019-feature-messier-35-an-open-star-cluster-in-gemini-copy/ Cor Caroli, The Heart of Charles], April 2019 Feature – University Television, Comcast 61/1095 & UVerse 99, University of Arkansas Little Rock, February 28, 2019. Retrieved 10 October 2025.
  2. "Cor Caroli", p. 49, ''The hundred greatest stars'', James B. Kaler, Springer, 2002, {{ISBN. 0-387-95436-8.
  3. Robert Burnham, Jr. ''Burnham's Celestial Handbook'', Volume 1, p. 359.
  4. R.H. Allen, ''Star Names: Their Lore and Meaning''.
  5. "* alf01 CVn".
  6. "* alf02 CVn".
  7. {{cite Gaia EDR3. 1517698613271954304
  8. {{cite Gaia EDR3. 1517698716348324992

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canes-venaticibayer-objectsflamsteed-objectshenry-draper-catalogue-objectshipparcos-objectsa-type-main-sequence-starsf-type-main-sequence-starsbinary-starsalpha2-canum-venaticorum-variablesstars-with-proper-namesdurchmusterung-objectsbright-star-catalogue-objectslucidae