Alnilam


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 (Vol. I-III)


catalogues and names Alnilam, e Ori, eps Ori, 46 Ori, HR 1903, HD 37128, SAO 132346, FK5: 210, WDS 05362-0112
other names Alnihan, Alnitam
constellation Orion

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

note (category: star names): ALNILAM; Alnihan; Alnitam.

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

position, motion, parallax:

position (J2000) RA: 5h 36min 12,8sec DEC: -1 12' 7''
position (J1900) RA: 5h 31min 8,3sec DEC: -1 15' 57''
proper motion (J2000) RA: 0,001 arcsec/a DEC: -0,002 arcsec/a
radial velocity 26 km/s
note: spectroscopic binaries
rotational velocity 87 km/s (uncertain) (variable)
trigonometric parallax -0,002 arcsec
note (category: radial and/or rotational velocities): UV AEROBEE spectra indicate mass ejection at velocity up to 1800k/s.

magnitude

visual magnitude 1,7
(V on UBV Johnson system)

spectral / color information

spectral class B0Ia
B-V-magnitude -0,19
U-B-magnitude -1,04
R-I-magnitude -0,17
note (category: spectra): Nitrogen deficient. Interstellar Lyman alpha absorption observed by AEROBEE rocket. Walborn declares "no e", but Merrill found H alpha emission.
note (category: colors): In both infrared survey and UV CELESCOPE. Color excess E(B-V) = +0.08.

variability information

variable star identification Eps Ori
note (category: variability): Alpha Cyg 1.64 - 1.74V.

double/multiple star system information

separation 179,9 arcsec
mag difference (of double or brightest multiple) 8,7
note Worley (1978) update of the IDS

miscellaneous information

note (category: group membership): Ori OB1b2; Orion belt; cluster NGC 1980; nebulosity.
note (category: stellar radii or diameters): Diam. = 0.00067 - 0.00069".

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

position, motion, parallax:

position (J2000) RA: 5h 36min 12,809sec DEC: -1 12' 7,02'' 0,06 arcsec source: 15
proper motion (J2000) RA: 0,0001 arcsec/a DEC: -0,002 arcsec/a source: 25
radial velocity 26 km/s source: 25
galactic coord. (B1950) longitude: 205,22 latitude: -17,24
GCI unit vector (J2000) X: 0,103579 Y: 0,9944 Z: -0,020976

magnitude:

visual 1,6 (observed) source: 31
photovisual 1,8 source: 2

spectral information:

spectral class B0 source: 96
Morgan-Keenan B0Ia source: 25
B-magnitude 1,51 0,05 B-V-magnitude -0,19
U-magnitude 0,47 0,05 U-B-magnitude -1,04

variability information:

source of data: 30
variability type 133
var. amplitude 0,1

double/multiple star system information:

source of data: 19
separation between brightest and second brightest component 179,9 arcsec
magnitude difference between brightest and second brightest component 8,8
position angle 57

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
15 FK5, FK5 Extension and FK5 Supplement
Fricke, W., H. Schwan and T. Lederle, "Fifth Fundamental Catalogue (FK5), Part I. The Basic Fundamental Stars," Veroff. Astronomisches Recheninstitut, No. 32, Heidelberg, Germany, 1988, and Fricke, W., H. Schwan, and T.E. Corbin, "Fifth Fundamental Catalogue (FK5), Part II. The FK5 Extension," Veröff. Astronomisches Recheninstitut, No. 33, Heidelberg, Germany, 1991
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
30 GCVS, 4th edition
Kholopov, P.N., et al., General Catalogue of Variable Stars, fourth edition, Moscow: Nauka Publishing House, 1985-88
31 CRM' (non-GCVS variable data)
Warren, W.H. Jr., Northern Hemisphere Catalog of Red Magnitudes, 1994
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 33min 40,476sec DEC: -1 13' 56,3'' 0,004 arcsec
position (J2000) RA: 5h 36min 12,812sec DEC: -1 12' 7,05''
proper motion J1950 (FK4) RA: -0,0002 arcsec/a DEC: -0,002 arcsec/a 0,001 arcsec/a in RA
0,001 arcsec/a in DEC
proper motion J2000 (FK5) RA: 0,0001 arcsec/a DEC: -0,002 arcsec/a
source of proper motion data Determined by source catalog

magnitude:

visual 1,8 (accuracy: 2 decimals)
source of visual magnitude data Taken from the "Henry Draper Catalogue".

spectral information:

spectral class B0
source of spectral data Taken from the Henry Draper Catalogue or no spectrum in source catalog.

catalogues

source catalogue FK4, catalogue number: 210
Durchmusterung BD-01 969
Boss General Catalogue 6960
Henry Draper Catalogue 37128

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

position and proper motion:

position (J2000) RA: 5h 36,2min DEC: -1 12'
proper motion (J2000) RA: 0,001 arcsec/a DEC: -0,002 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
- 1879 2 57 179,9'' 1,7 10,5 B0Iae BUP 81

discoverer information:

discoverer code discoverer reference
BUP 81 - -

notes:

note Epsilon Ori. Possibly variable.

data from Combined General Catalogue of Variable Stars (Vol. I-III) (Kholopov+ 1998)

position:

position (J1950) RA: 5h 33min 40sec DEC: -1 13' 54'' 1 sec / 0.1 arcmin

variability informations:

variability type ACYG pulsating variable star
magnitute at max. brightness 1,64
magnitute at min. brightness 1,74
photometric system visual, photovisual or Johnson's V

spectral information

spectral class B0.5Iabea

references

to a study Vol. I GCVS (see Kholopov et al. 1985-1988)
to a chart/photograph Vol. I GCVS (see Kholopov et al. 1985-1988)

miscanellous

ID in the GCVS catalogue 60/9005
constellation Orion
notes on existence The star is equivalent to '0609007 eta'.
There are notes in published catalog.

variability type description

variability type description
ACYG Variables of the Alpha Cygni type, which are nonradially pulsating supergiants of Bep-AepIa spectral types. The light changes with amplitudes of the order of 0.1 mag often seem irregular, being caused by the superposition of many oscillations with close periods. Cycles from several days to several weeks are observed.