Cor caroli2

(kor KAR-o-leye)

Alpha2 Canum Venaticorum

Cor caroli

Distance (Light Years) 110 ± 4
Apparent Magnitude 2.89
Color (B-V)-0.12

Names For This Star

The star name Cor Caroli is Latin and means "Charles' Heart." The star was named by Edmund Halley, the Astronomer Royal, in 1725 to honor King Charles II of Great Britain. The star commemorates the restoration of the monarchy after the British Civil War.

An authority quoted by Burnham gives the original name of the star as Cor Caroli Regis Martyris, that is, "The Heart of Charles, The Martyred King" in honor of King Charles I, who was executed when the British monarchy was overthrown by Puritans in the British Civil War. Burnham finds the attribution of the name to Halley in an 1801 publication, but can find no other verification for Halley as the creator of the name.

Description of the Star

Cor Caroli is a binary star system. The two stars are separated by 20 sec of arc, corresponding to a projected separation of 680 AU. The two stars seem to be a physical system, since they share a common proper motion (see Burnham). However, no change in the relative position of the stars has been observed since 1830. This indicates that the orbital period of the pair must be very long. You can find information on the companion here.

Alpha2 Canum Venaticorum at magnitude 2.89 is the brighter star of the pair. This star is a white star of spectral type A0pSiEuHg, that is, the star shows a peculiar spectrum characterized by unusual strength of certain metallic lines. The star is also characterized by a remarkably strong magnetic field.

The star is 4 times the diameter of the sun and about 68 times as luminous. The star varies in light output by 0.03 magnitude with a period of 5.5 days. The variation in brightness is accompanied by variation of magnetic field. According to Burnham Alpha2 is the prototype star and standard example of a magnetic spectrum variable.

Other Designations For This Star


12 Canum Venaticorum

Hipparcos Identifier (HIP Number)


Harvard Revised (HR Number)


Henry Draper Catalog (HD Number)


Bonner Durchmusterung (BD Number)

BD+39 2580
Smithsonian Astrophysical
Observatory compendium (SAO Number)

Fundamental Katalog (FK5 Number)



Copyright © 1998 - 2010 by Arnold V. Lesikar,
Professor Emeritus
Dept. of Physics, Astronomy, and Engineering Science,
St. Cloud State University,St. Cloud, MN 56301-4498

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