Alnitak, a blue supergiant star in Orion

Alnitak (HIP 26727)

Alnitak is a blue supergiant star in the constellation Orion. At 1,088 light years away, it is the 32nd brightest star in the Earth's sky, where it shines at an apparent visual magnitude of 1.74. Alnitak is a multiple-star system. It is moving through the Galaxy at a speed of 19.4 km/s relative to the Sun and is part of the Orion Molecular Cloud and Collinder 70 moving groups. Its projected Galactic orbit carries it between 25,100 and 30,800 light years from the center of the Galaxy.

Sky position: RA 5h 40.8m, Dec -1° 56.4'

Common designations: Alnitak, Zeta Orionis, 50 Orionis, HIP 26727, HD 37742

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Stars of the Northern Hemisphere
Deluxe Astronomy Poster Brightest stars in Orion:
(list all)

Rank	Mag.	Star
1	0.18	Rigel
2	0.45	Betelgeuse
3	1.64	Bellatrix
4	1.69	Alnilam

5

| 1.74

) Alnitak

Rank	Mag.	Star
6	2.07	Saiph
7	2.25	Mintaka
8	2.75	Hatsya
9	3.19	Tabit
10	3.35	Eta Orionis
11	3.39	Heka
12	3.59	Tau Orionis
13	3.68	Pi-4 Orionis
14	3.71	Pi-5 Orionis
15	3.77	Sigma Orionis
16	4.06	Omicron-2 Orionis
17	4.09	Phi-2 Orionis

Location of Alnitak circled Map detail from Stars of the Northern Hemisphere
Hover over other bright stars to identify or click to jump.

Galactic Orbit of Alnitak
(compared to the Sun)

E

ccentricity: 10.4% vs. 16.0%

Angle φ : 0.8°vs. 26.0°

Semi-major axis : 8,575 pc vs. 8,686 pc

Semi-minor axis: 8,529 pc vs. 8,574 pc

Focus-to-center

: 887 pcvs. 1,388 pc

Semilatus rectum : 8,484 pc vs. 8,464 pc

Perigalacticon: 7,688 pc vs. 7,297 pc

Apogalacticon

: 9,462 pcvs. 10,074 pc
  Some Tabulated XHIP Data for Alnitak
(see also: SIMBAD)

Astrometry
2007A&A...474..653V

Position	Proper Motion
Right Ascension:	85.18968667° ±0.52 mas	3.19 ±0.59 mas/yr.
Declination:	-1.94257852° ±0.25 mas	2.03 ±0.26 mas/yr.
Galactic Longitude:	206.45217979°	-0.31 mas/yr.
Galactic Latitude:	-16.58517589°	3.77 mas/yr.

Parallax: 4.43 ± 0.64 mas

Spectrography

Spectral Type: O9.5I 1971ApJ...170..325C.

Radial Velocity: 18.50 ±1.30 km/s [B rating] 2007AN....328..889K.

Iron Abundance [Fe/H]: n/a

Photometry
 

band	magnitude	Abs. Mag.
U
B	1.54	-6.08
V	1.74	-5.88
R
I	1.88	-5.74
J
H
K

B-V: -0.20 V-I: -0.14

Derivations

Heliocentric distance: 333.85 pc (fitted to cluster)

Galactocentric distance: 7,688 pc

Transverse velocity: 6.0 km/s

3D heliocentric position and motion:

toward:	Galactic center	Galactic rotation	North Galactic Pole
Position ( X, Y, Z)	-286.5 pc	-142.5 pc	-95.3 pc
Velocity (U, V, W)	-17.6 km/s	-8.2 km/s	0.4 km/s