Designations
- Flamsteed: 80 UMa
- Hipparchos: HIP 65477
Data
- Constellation: Ursa Major
- Apparent Magnitude: 4.01
- Right Ascension (J2000): 13h25m13.31s
- Declination (J2000): +54°59'34".3
- Colour Index (B-V): 0.17
- Distance: 80.61±0.28ly
Description
The star Alcor itself is a double star and is gravitationally bound to the nearby quadruple star Mizar (ζ UMa), forming a sextuple system. The pair forms a naked eye binary, used a visual test since ancient times.
Nomenclature
Alcor
Ultimately, Alcor is derived from the indigenous title for ε UMa al-Ğawn, 'the black horse'. The name was transliterated and variously corrupted, with the corruption Alcor being misapplied as a star name to 80 UMa in Renaissance times.