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Alpha CVn (HIP 63125)

COR CAROLI

Observable Double Star Excellent (68/100)

Sep: 19.2", Companion: mag 5.5

Observable Variable Star

Range: 2.84 - 2.98, Period: 5.5d, Type: ACV

HIP 63125; Alpha2 CVn; 12 CVn DoubleStar CVn Visible Level 2 Small telescope (4") - Requires steady seeing
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Physical Properties

Magnitude 2.90
Range 2.84 - 2.98
Period 5.469 days
Variable Type Alpha2 CVn (Magnetic Rotating)
Spectral Type B7V
Star Color Blue-white (B-V -0.12)
Distance 114.7 ly

Position & Identifiers

RA 12h 56m 01.7s
Dec +38° 19' 06.0"
Constellation CVn
HR 4915
HIP 63125
Bayer Alpha2
Flamsteed 12 CVn
Variable ID Alp2 CVn
Double Cat 8706

Visibility

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Light Curve

Comparison Stars

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Multiple Star System

Separation 19.2″
Companion Mag 5.5
Position Angle 229°
Star Colors A: Blue-white B: Yellow-white
Discoverer STF1692

Eyepiece View

80x Dawes: 1.9″ TFOV: 0.6°
Realistic = true angular size
N E 229° A (2.9) B (5.5)

Sep: 19.2″ · PA: 229° · N up, E left

Resolved · Rayleigh: 2.3″ · Dawes: 1.9″ · Eff: 3.1″

Size Comparison

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Stellar Lifecycle

Spectral Classification

Hertzsprung-Russell Diagram

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Blackbody Spectrum

Stellar Absorption Spectrum

Simulated absorption spectrum based on spectral type. Hover over lines to identify elements.

Stellar Notes

ADS 8706A, Alpha CV 2.84 - 2.98V, 2.78 - 2.81B, 5.46939d. The prototype star. Var. magnetic field with same rotation | period.
Binary with HR 4914.
Hyades group.
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.).
0.015".
COR CAROLI.
Radius relative to Sun = 4.1.

Survey Image

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About Alpha CVn (HIP 63125)

Description

Cor Caroli is a chemically peculiar star of spectral type A0pSiEuHg at magnitude 2.90, the brightest star in Canes Venatici (the Hunting Dogs). Located about 110 light-years from Earth, it is the prototype of the Alpha2 Canum Venaticorum class of magnetic variable stars, with starspots of concentrated silicon, europium, and mercury. It is a wide double with a fainter companion visible in small telescopes.

Observing Tips

Cor Caroli lies below the handle of the Big Dipper, about 7 degrees south of Alkaid. A small telescope reveals the companion (magnitude 5.5) about 19 arcseconds away. It is the starting point for finding the Whirlpool Galaxy (M51) and other Canes Venatici deep-sky objects. Best observed March through July.

History

The name Cor Caroli means 'the Heart of Charles,' named by Edmund Halley in honor of King Charles I of England (some sources say Charles II). It is one of the few bright stars named after a modern historical figure rather than derived from Arabic or classical sources.

Fun Facts

Cor Caroli defines an entire class of chemically peculiar variable stars. Its strong magnetic field concentrates rare elements into spots on its surface, causing small brightness variations as it rotates — a stellar version of sunspots, but driven by magnetic chemistry.