Alnitak

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Alnitak Aa/Ab/B
Ngc2024 2mass.jpg
Alnitak (in lawer richt corner) an Flame Nebula
Observation data
Epoch J2000      Equinox J2000
Constellation Orion
Richt ascension 05h 40m 45.5s
Declination −01° 56′ 34″
Apparent magnitude (V) 2.0/~4/4.21
Characteristics
Spectral type O9 Iab/O9/B0 III
U−B colour index −1.07
B−V colour index 0.14 / ? / −0.01
Astrometry
Radial velocity (Rv) 18 km/s
Proper motion (μ) RA: 3.19 mas/yr
Dec.: 2.03 mas/yr
Parallax (π) 4.43 ± 0.64 mas
Distance approx. 700 ly
(approx. 230 pc)
Absolute magnitude (MV) −5.25/−3/−2.8
Details
Mass 28/23/20 M
Radius 20/? R
Luminosity 100,000/1,300/? L
Temperatur 30,000/?/24,000 K
Metallicity ?
Rotation 140 km/s / ?
Age ? years
Ither designations
ζ Orionis, 50 Orionis, 126 G. Orionis, HR 1948/9, BD −02°1338, HD 37742, SAO 132444, HIP 26727, TD1 5127, 參宿一.
Database references
SIMBAD data

Alnitak (Arabic: النطاق an-niṭāq‎) is a triple starn some 736 licht years distant in the constellation Orion. It is pairt o Orion's Belt alang wi Alnilam an Mintaka, an haes a Bayer designation o Zeta Orionis.

The primary starn is a het blue supergiant wi an absolute magnitude o -5.25, an is the brichtest class O starn in the nicht sky wi a veesual magnitude o +2.04. It haes twa bluish 4t magnitude companions, producin a combined magnitude for the trio o +1.72. The starns are members o the Orion OB1 association an the Collinder 70 association.