Alcor (star)

Alcor
Location of Alcor (Mizar is circled, Alcor is invisible beside it at this scale.)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Ursa Major
Right ascension 13h 25m 13.53783s[1]
Declination +54° 59′ 16.6548″[1]
Apparent magnitude (V) +3.99[2]
Characteristics
Spectral type A5Vn[3] / M3-4[4]
Astrometry
Radial velocity (Rv)−9.6[5] km/s
Parallax (π)39.91 ± 0.13 mas[1]
Distance81.7 ± 0.3 ly
(25.06 ± 0.08 pc)
Absolute magnitude (MV)+2.00[2]
Details
Alcor A
Mass1.84[6] M☉
Radius1.846[7] R☉
Luminosity14.03[6] L☉
Surface gravity (log g)4.25[8] cgs
Temperature8,221[8] K
Rotational velocity (v sin i)228[6] km/s
Alcor B
Mass0.25[4] M☉
Age0.5 ± 0.1[2] Gyr
Other designations
g Ursae Majoris, 80 Ursae Majoris, BD+55 1603, CCDM J13240+5456D, GC 18155, HD 116842, HIP 65477, HR 5062, PPM 34021, SAO 28751, WDS J13239+5456C
Database references
SIMBADdata

Alcor (/ˈælkɔːr/)[9] is a binary star system in the constellation of Ursa Major. It is the fainter companion of Mizar, the two stars forming a naked eye double in the handle of the Big Dipper (or Plough) asterism in Ursa Major. The two lie about 83 light-years away from the Sun, as measured by the Hipparcos astrometry satellite.

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