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Mizar and Alcor

Mizar
Mizar and Alcor in constellation Ursa Major
Mizar and Alcor in constellation Ursa Major
Observation data
Epoch J2000      Equinox J2000
Constellation Ursa Major
Right ascension 13h 23m 55.5s
Declination +54° 55′ 31″
Apparent magnitude (V) 2.27
Characteristics
Spectral type A2Vp/A2Vp/A1m/A5V
B−V color index 0.02
Astrometry
Radial velocity (Rv) −6.31 km/s
Proper motion (μ) RA: 119.01 mas/yr
Dec.: −25.97 mas/yr
Parallax (π) 38.01 ± 1.71mas
Distance 86 ± 4 ly
(26 ± 1 pc)
Absolute magnitude (MV) 0.33
Other designations
Mizat, Mirza, Mitsar, Vasistha, ζ Ursae Majoris, ζ UMa, Zeta UMa, 79 Ursae Majoris, BD+55 1598A, CCDM J13240+5456AB, FK5 497, GC 18133, HD 116656, HIP 65378, HR 5054, PPM 34007, SAO 28737, WDS J13239+5456Aa,Ab.
Database references
SIMBAD data
Alcor
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Ursa Major
Right ascension 13h 25m 13.5s
Declination +54° 59′ 17″
Apparent magnitude (V) +3.99
Absolute magnitude (V) +2.00
Distance 81.7 ± 0.2 ly
(25.1 ± 0.08 pc)
Spectral type A5Vn / M
Other designations
Saidak, Suha, Arundhati, 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+5456Ca,Cb.
Database references
SIMBAD data

Mizar and Alcor are two stars forming a naked eye double star in the handle of the Big Dipper (or Plough) asterism in the constellation of Ursa Major. Mizar is the second star from the end of the Big Dipper's handle, and Alcor its faint companion.

Mizar, also designated Zeta Ursae Majoris (ζ Ursae Majoris, abbreviated Zeta UMa, ζ UMa), is itself a quadruple system and Alcor, also designated 80 Ursae Majoris (80 UMa), is a binary, the pair together forming a sextuple system. The whole system lies about 83 light-years away from the Sun, as measured by the Hipparcos astrometry satellite.

ζ Ursae Majoris (Latinised to Zeta Ursae Majoris) is Mizar's Bayer designation. 80 Ursae Majoris is Alcor's Flamsteed designation.

The traditional name Mizar derives from the Arabic المئزر miʼzar meaning 'apron; wrapper, covering, cover'.Alcor was also originally Arabic سها suhā, meaning either the ‘forgotten’ or ‘neglected’ one.; notable as a faintly perceptible companion of Mizar.

In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016 included a table of the first two batches of names approved by the WGSN; which included Mizar for Zeta UMa and Alcor for 80 UMa. They are now so entered in the IAU Catalog of Star Names.


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Wikipedia

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