Alnitak


The object was found in the following catalogues:
  1. The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version)

  2. SKY2000 - Master Star Catalog

  3. Smithsonian Astrophysical Observatory Star Catalog

  4. The Washington Visual Double Star Catalog, 1996.0

  5. Combined General Catalogue of Variable Stars (suspected variables)


catalogues and names Alnitak, z Ori, NSV 02553, 50 Ori, HR 1948, HD 37742, SAO 132444, WDS 05407-0157A
other names Alnitah
constellation Orion

data from The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version) (Hoffleit+, 1991)

note (category: star names): ALNITAK; Alnitah.

object is infrared source (NASA merged infrared catalogue, Schmitz et al., 1978)

position, motion, parallax:

position (J2000) RA: 5h 40min 45,5sec DEC: -1 56' 34''
position (J1900) RA: 5h 35min 42,7sec DEC: -1 59' 43''
proper motion (J2000) RA: 0,003 arcsec/a DEC: -0,002 arcsec/a
radial velocity 18 km/s
note: spectroscopic binaries
rotational velocity 140 km/s (uncertain) (variable)
trigonometric parallax 0,024 arcsec
note (category: radial and/or rotational velocities): Mass ejection up to 1800k/s.
note (category: dynamical parallaxes): 0.004".

magnitude

visual magnitude 2,05
(original HR magnitude)

spectral / color information

spectral class O9.7Ib
B-V-magnitude -0,21
U-B-magnitude -1,07
R-I-magnitude -0,2
note (category: spectra): Nitrogen deficient. Interstellar Lyman alpha absorption observed by AEROBEE rocket. Also classified O9.5Ib and O9.5Iab.
note (category: colors): Color excess E(B-V) = +0.09.

variability information

variable star identification 2553
note (category: variability): ADS 4263. Uncertain which component, HR 1948 or 1949, is the variable suspect.

double/multiple star system information

number of components of multiple star system 3
separation 2,4 arcsec
mag difference (of double or brightest multiple) 2,2
component ID AB
note (category: double and multiple data): AB 1.88 O9.5Ib, 4.02 B2III, 1508.6y, a = 2.728". Colors for combined light. Blended magnitude 1.76V, 18 and 6 solar masses. B is HR 1949. C is 9v at 58", possibly physical.

miscellaneous information

note (category: group membership): Ori OB1b1; Orion belt; exciting star of HII region S277; HII region; IC 434.
note (category: stellar radii or diameters): Diam. = 0.00047 - 0.00048".
note (category: miscellaneous): In line of sight of high-velocity interstellar cloud.

data from SKY2000 - Master Star Catalog (Myers+ 1997)

position, motion, parallax:

position (J2000) RA: 5h 40min 45,524sec DEC: -1 56' 33,53'' 1,48 arcsec source: 29
proper motion (J2000) RA: 0,0002 arcsec/a DEC: -0,002 arcsec/a source: 25
radial velocity 18 km/s source: 25
trigonometric parallax 0,024 0,002 arcsec source: 25
galactic coord. (B1950) longitude: 206,46 latitude: -16,59
GCI unit vector (J2000) X: 0,083809 Y: 0,995905 Z: -0,033899

magnitude:

visual 2,03 (observed) source: 25
photovisual 2,1 source: 2
photographic 1,8 source: 2

spectral information:

spectral class B0 source: 96
Morgan-Keenan O9.7Ib source: 25
B-magnitude 1,82 0,05 B-V-magnitude -0,21
U-magnitude 0,78 0,05 U-B-magnitude -1,04

double/multiple star system information:

source of data: 19
separation between brightest and second brightest component 2,3 arcsec
magnitude difference between brightest and second brightest component 2,2
position angle 166

component magnitude spectral class catalogue(s)/name(s)
A 2,03 B0 Alnitak, z Orionis, 50 Ori, HR 1948, HD 37742, SAO 132444
B 4,21 - z Orionis, 50 Ori, HR 1949, HD 37743,

sources:

2 HD and HDE Catalogs
Cannon, A.J., and E.C. Pickering, Harvard Annals, Vols 91-99, 1918-24, Cambridge, Massachusetts: Harvard University; Cannon, A.J., Harvard Annals, Vol. 100, 1925-36, Cambridge, Massachusetts: Harvard University; and Cannon, A.J., and M. Walton Mayall, Harvard Annals, Vol. 112, 1949, Cambridge, Massachusetts: Harvard University
19 WDS Catalog
Worley, C.E., and G.G. Douglass, Washington Catalog of Visual Double Stars 1996.0, United States Naval Observatory, 1996
25 Bright Star Catalogue, 5th edition
Hoffleit, D. and Warren, W.H. Jr., The Bright Star Catalogue, 5th Revised Edition, Version 2, 1994
29 SAOJ2000
SAO on FK5 at J2000, 1989
96 SAO or HD/HDE Catalog
Reference from Value 1 or Reference from Value 2

data from Smithsonian Astrophysical Observatory Star Catalog (SAO Staff 1966; USNO, ADC 1990)

position and proper motion:

position (J1950) RA: 5h 38min 14,043sec DEC: -1 58' 2,98'' 0,006 arcsec
position (J2000) RA: 5h 40min 45,524sec DEC: -1 56' 33,53''
proper motion J1950 (FK4) RA: -0,0001 arcsec/a DEC: -0,002 arcsec/a 0,001 arcsec/a in RA
0,001 arcsec/a in DEC
proper motion J2000 (FK5) RA: 0,0002 arcsec/a DEC: -0,002 arcsec/a
source of proper motion data Determined by source catalog

magnitude:

visual 2 (accuracy: 2 decimals)
source of visual magnitude data Combined magnitude of component stars.

spectral information:

spectral class B0
source of spectral data Taken from the HD with M stars reclassified by Miss Cannon.

remarks for duplicity and variability

Double star - see source catalog for source

catalogues

source catalogue FK3, catalogue number: 1631
Durchmusterung BD-02 1338
Boss General Catalogue 7089
Henry Draper Catalogue 37742
The "SAO Catalog" entry refers to two consecutive HD numbers, the lower of which is given.

data from The Washington Visual Double Star Catalog, 1996.0 (Worley+, 1996)

position and proper motion:

position (J2000) RA: 5h 40,7min DEC: -1 57'
proper motion (J2000) RA: 0,001 arcsec/a DEC: -0,005 arcsec/a

double/multiple star system information:

component year number of measures position angle angular separation magnitude of 1st component magnitude of 2nd component spectral class(es) discoverer code
AB 1822 often 151 2,3'' 2 4,2 O9.5Ibe STF 774
1990 166 -
AC 1880 13 10 57,6'' 2 10 - STF 774
BC 1909 1 8 59,7'' 4,2 8,5 B0 STF 774

discoverer information:

discoverer code discoverer reference
STF 774 Struve, F.G.W. -

notes:

note Zeta Ori. A premature orbit has been computed. Variable radial velocity of A not confirmed. C may be physical. Spectral types of AB: O9.5Ibe and B0III.

data from Combined General Catalogue of Variable Stars (suspected variables) (Kholopov+ 1998)

position:

position (J1950) RA: 5h 38min 14sec DEC: -1 58' 3''

variability informations:

magnitute at max. brightness 1,72
magnitute at min. brightness 1,79
photometric system visual, photovisual or Johnson's V

spectral information

spectral class O9

references

to a study 480402D (designation: zeta ORI)

miscanellous

There are notes in the published catalog (Kukarkin et al.(1982)).