Cor Caroli
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| Observation data Equinox J2000.0 |
|
|---|---|
| Constellation | Canes Venatici |
| Right ascension | 12h56m01.7s |
| Declination | +38°19′06″ |
| Apparent magnitude (V) | +2.89/+5.61 |
| Distance | 110 ± 4 ly (34 ± 1 pc) |
| Spectral type | F0V/A0pSiEuHg |
| Other designations | |
Cor Caroli (α CVn / α Canum Venaticorum / Alpha Canum Venaticorum) is the brightest star in the northern constellation Canes Venatici. The name Cor Caroli means Charles' heart, and was named most likely by Edmond Halley in honour of either Charles I, who was executed or Charles II of England, his son, who was restored to the throne after the interregnum following his father's death.
Cor Caroli is a binary star which has a combined apparent magnitude of +2.89. The two stars are 19.6 arcseconds apart on the sky and are easily resolved in small telescopes. It is approximately 110 light years from Earth.
The main star, α² Canum Venaticorum, is the prototype of a class of variable stars, the so-called α² Canum Venaticorum stars. These stars have a strong magnetic field, which is believed to produce sunspots of enormous extent. Due to these sunspots the brightness of α² Canum Venaticorum stars varies considerably during their rotation.
The brightness of α² Canum Venaticorum varies between +2.84 magnitude and +2.94 with a period of 5.47 days. Its spectral type is A0. The companion, α¹ Canum Venaticorum, of spectral type F0, is considerably fainter at +5.5 magnitude.
Cor Caroli marks the northern vertex of the Diamond of Virgo asterism.
