Mizar (star)
 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 | |
| Database references | |
| SIMBAD | data |
| 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 | |
| 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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