Cor Caroli

The object was found in the following catalogues:
  1. The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version)

  2. SKY2000 - Master Star Catalog

  3. Smithsonian Astrophysical Observatory Star Catalog

  4. The Washington Visual Double Star Catalog, 1996.0

  5. Combined General Catalogue of Variable Stars (Vol. I-III)

catalogues and names Cor Caroli, a2Cvn, alf 2 CVn, 12 Cvn, HR 4915, HD 112413, SAO 63257, FK5: 485, WDS 12560+3819
constellation Canes Venatici

data from The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version) (Hoffleit+, 1991)

note (category: star names): COR CAROLI.

object is infrared source (NASA merged infrared catalogue, Schmitz et al., 1978)

position, motion, parallax:

position (J2000) RA: 12h 56min 1,7sec DEC: +38 19' 6''
position (J1900) RA: 12h 51min 21sec DEC: +38 51' 30''
proper motion (J2000) RA: -0,234 arcsec/a DEC: 0,056 arcsec/a
radial velocity -3 km/s
note: variable radial velocity
rotational velocity 29 km/s (uncertain) (variable)
trigonometric parallax 0,027 arcsec
note (category: dynamical parallaxes): 0.015".


visual magnitude 2,9
(V on UBV Johnson system)

spectral / color information

spectral class A0pSiEuHg
B-V-magnitude -0,12
U-B-magnitude -0,32
R-I-magnitude -0,06
note (category: spectra): Oxygen deficient relative to magnesium. A slight underabundance of Mg. Strong Si and Eu lines. Also classified A0IIIp, A1IV-Vp (Si v. st., Ca v. wk.).

variability information

variable star identification Alp2 CVn
note (category: variability): ADS 8706A, Alpha CV 2.84 - 2.98V, 2.78 - 2.81B, 5.46939d. The prototype star. Var. magnetic field with same rotation period.

double/multiple star system information

separation 19,4 arcsec
mag difference (of double or brightest multiple) 2,7
note (category: double and multiple data): Binary with HR 4914.

miscellaneous information

note (category: group membership): Hyades group.
note (category: stellar radii or diameters): Radius relative to Sun = 4.1.

data from SKY2000 - Master Star Catalog (Myers+ 1997)

position, motion, parallax:

position (J2000) RA: 12h 56min 1,664sec DEC: +38 19' 6,21'' 0,06 arcsec source: 15
proper motion (J2000) RA: -0,0199 arcsec/a DEC: 0,056 arcsec/a source: 25
radial velocity -3 km/s source: 25
trigonometric parallax 0,027 0,003 arcsec source: 25
galactic coord. (B1950) longitude: 118,26 latitude: 78,77
GCI unit vector (J2000) X: -0,761249 Y: -0,189899 Z: 0,620031


visual 2,8 (observed) source: 31
photovisual 2,9 source: 2

spectral information:

spectral class A0 source: 96
Morgan-Keenan A0pSiEuHg source: 25
B-magnitude 2,78 0,05 B-V-magnitude -0,12
U-magnitude 2,46 0,05 U-B-magnitude -0,32

variability information:

source of data: 30
variability type 160
var. amplitude 0,14
var. period 5,47
var. epoch 2439013
9. September 1965, 12:00:00 UT
next max light 2451621,35
17. March 2000, 20:24:00 UT

double/multiple star system information:

source of data: 19
separation between brightest and second brightest component 19,3 arcsec
magnitude difference between brightest and second brightest component 2,71
position angle 228

component magnitude spectral class catalogue(s)/name(s)
A 2,8 A0 Cor Caroli, a2Canum Venaticorum, 12 Cvn, HR 4915, HD 112413, SAO 63257
B 5,6 A0p a1Canum Venaticorum, 12 Cvn, HR 4914, HD 112412, SAO 63256


2 HD and HDE Catalogs
Cannon, A.J., and E.C. Pickering, Harvard Annals, Vols 91-99, 1918-24, Cambridge, Massachusetts: Harvard University; Cannon, A.J., Harvard Annals, Vol. 100, 1925-36, Cambridge, Massachusetts: Harvard University; and Cannon, A.J., and M. Walton Mayall, Harvard Annals, Vol. 112, 1949, Cambridge, Massachusetts: Harvard University
15 FK5, FK5 Extension and FK5 Supplement
Fricke, W., H. Schwan and T. Lederle, "Fifth Fundamental Catalogue (FK5), Part I. The Basic Fundamental Stars," Veroff. Astronomisches Recheninstitut, No. 32, Heidelberg, Germany, 1988, and Fricke, W., H. Schwan, and T.E. Corbin, "Fifth Fundamental Catalogue (FK5), Part II. The FK5 Extension," Veröff. Astronomisches Recheninstitut, No. 33, Heidelberg, Germany, 1991
19 WDS Catalog
Worley, C.E., and G.G. Douglass, Washington Catalog of Visual Double Stars 1996.0, United States Naval Observatory, 1996
25 Bright Star Catalogue, 5th edition
Hoffleit, D. and Warren, W.H. Jr., The Bright Star Catalogue, 5th Revised Edition, Version 2, 1994
30 GCVS, 4th edition
Kholopov, P.N., et al., General Catalogue of Variable Stars, fourth edition, Moscow: Nauka Publishing House, 1985-88
31 CRM' (non-GCVS variable data)
Warren, W.H. Jr., Northern Hemisphere Catalog of Red Magnitudes, 1994
96 SAO or HD/HDE Catalog
Reference from Value 1 or Reference from Value 2

data from Smithsonian Astrophysical Observatory Star Catalog (SAO Staff 1966; USNO, ADC 1990)

position and proper motion:

position (J1950) RA: 12h 53min 41,478sec DEC: +38 35' 16,82'' 0,004 arcsec
position (J2000) RA: 12h 56min 1,67sec DEC: +38 19' 6,22''
proper motion J1950 (FK4) RA: -0,0201 arcsec/a DEC: 0,052 arcsec/a 0,001 arcsec/a in RA
0,001 arcsec/a in DEC
proper motion J2000 (FK5) RA: -0,0198 arcsec/a DEC: 0,057 arcsec/a
source of proper motion data Determined by source catalog


visual 2,9 (accuracy: 2 decimals)
source of visual magnitude data Taken from the "Henry Draper Catalogue".

spectral information:

spectral class A0p
source of spectral data Taken from the Henry Draper Catalogue or no spectrum in source catalog.


source catalogue FK4, catalogue number: 485
Durchmusterung BD+39 2580A
Boss General Catalogue 17557
Henry Draper Catalogue 112413

data from The Washington Visual Double Star Catalog, 1996.0 (Worley+, 1996)

position and proper motion:

position (J2000) RA: 12h 56min DEC: +38 19'
proper motion (J2000) RA: -0,234 arcsec/a DEC: 0,057 arcsec/a

double/multiple star system information:

component year number of measures position angle angular separation magnitude of 1st component magnitude of 2nd component spectral class(es) discoverer code
- 1822 71 228 20'' 2,9 5,61 A0pSiEuHg STF1692
1984 - 19,3''

discoverer information:

discoverer code discoverer reference
STF1692 Struve, F.G.W. -


note Alpha CVn. Both components are spectroscopic binaries. Prototype of the Alpha CVn-type variables. Proper motion of B -226 +060, spectrum F0V.

data from Combined General Catalogue of Variable Stars (Vol. I-III) (Kholopov+ 1998)


position (J1950) RA: 12h 53min 41,5sec DEC: +38 35' 17''

variability informations:

variability type ACV rotating variable star
magnitute at max. brightness 2,84
magnitute at min. brightness 2,98
photometric system visual, photovisual or Johnson's V
epoch for maximum light [JD] 2439012,61
9. September 1965, 02:38:24 UT
period [d] 5,46939
next maximum light [JD] 2451619,55395
16. March 2000, 01:17:41 UT
rising time 60 % of period

spectral information

spectral class B9.5Vp(Si-Cr-Eu)


to a study Vol. I GCVS (see Kholopov et al. 1985-1988)
to a chart/photograph no chart is avaible, but the star is contained in the 'Bonner Durchmusterung'


ID in the GCVS catalogue 13/90012
constellation Canis Minor
notes on existence The star is equivalent to '0140001 R'.
There are notes in published catalog.

variability type description

variability type description
ACV Alpha2 Canum Venaticorum variables. These are main-sequence stars with spectral types B8p-A7p and displaying strong magnetic fields.
Spectra show abnormally strong lines of Si, Sr, Cr, and rare earths whose intensities vary with rotation. They exhibit magnetic field and brightness changes (periods of 0.5-160 days or more). The amplitudes of the brightness changes are usually withine 0.01-0.1 mag in V.

Rapidly oscillating Alpha2 CVn variables. These are nonradially pulsating, rotating magnetic variables of Ap spectral type (DO Eri). Pulsation periods are in the range of 6-12 mmag (0.004-0.01 days), while amplitudes of light variation caused by the pulsation are about 0.01 mag in V. The pulsational variations are superposed on those caused by rotation.