Cor Caroli /ˌkɔːr ˈkærəlaɪ/ is a binary star designated Alpha Canum Venaticorum or α Canum Venaticorum. The International Astronomical Union uses the name "Cor Caroli" specifically for the brighter star of the binary.^[17] Alpha Canum Venaticorum is the brightest point of light in the northern constellation of Canes Venatici.

Quick Facts Apparent magnitude (V), Characteristics ...

α Canum Venaticorum

The location of α Canum Venaticorum (circled)
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Canes Venatici
α2 CVn
Right ascension	12h 56m 01.66622s[1]
Declination	+38° 19′ 06.1541″[1]
Apparent magnitude (V)	2.84 to 2.98[2]
α1 CVn
Right ascension	12h 56m 00.43258s[1]
Declination	+38° 18′ 53.3768″[1]
Apparent magnitude (V)	5.60[3]
Characteristics
α2 CVn
Spectral type	A0pSiEuHg[4]
U−B color index	−0.32[5]
B−V color index	−0.12[5]
Variable type	α2 CVn
α1 CVn
Spectral type	F2V[6]
U−B color index	−0.03[7]
B−V color index	+0.34[7]
Astrometry
α2 CVn
Radial velocity (Rv)	−4.1±0.2[8] km/s
Proper motion (μ)	RA: −235.08[1] mas/yr Dec.: 53.54[1] mas/yr
Parallax (π)	32.7227 ± 0.5844 mas[9]
Distance	100 ± 2 ly (30.6 ± 0.5 pc)
Absolute magnitude (MV)	0.16±0.08[10]
α1 CVn
Radial velocity (Rv)	−0.60 ± 0.9[11] km/s
Proper motion (μ)	RA: −232.86[1] mas/yr Dec.: 55.69[1] mas/yr
Parallax (π)	30.6121 ± 0.0666 mas[12]
Distance	106.5 ± 0.2 ly (32.67 ± 0.07 pc)
Details
α2 CVn
Mass	2.97±0.07[10] M☉
Radius	2.49±0.26[10] R☉
Luminosity	101±12[10] L☉
Surface gravity (log g)	3.9±0.1[10] cgs
Temperature	11,600±500[10] K
Rotation	5.46939 d[10]
Rotational velocity (v sin i)	18.4±0.5[10] km/s
Age	165+60 −70[10] Myr
α1 CVn
Mass	1.47±0.15[13] M☉
Radius	1.5[13] R☉
Surface gravity (log g)	4.25±0.22[13] cgs
Temperature	7,080[13] K
Rotational velocity (v sin i)	18[14] km/s
Other designations
α CVn, Alpha CVn, 12 CVn, BD+39° 2580, ADS 8706 AB, CCDM J12560+3819B[15]
α2 CVn: α CVn A, 12 CVn A, FK5 485, GC 17557, HD 112413, HIP 63125, HR 4915, SAO 63257[15]
α1 CVn: α CVn B, 12 CVn B, GC 17556, HD 112412, HIP 63121, HR 4914, SAO 63256[16]
Database references
SIMBAD	α2 CVn
	α1 CVn

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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.^[18]

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.^[19] 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".^[20] 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.^[21]

In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)^[22] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016^[23] 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.^[24] Consequently, the Chinese name for Alpha Canum Venaticorum itself is 常陳一 (Cháng Chén yī, English: the First Star of Imperial Guards).^[25] From this Chinese name, the name Chang Chen was derived.^[26]

Alpha Canum Venaticorum is a binary star with 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. The system lies approximately 110 light-years from the Sun.

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

Cor Caroli was a U.S. Navy Crater-class cargo ship named after the star.