Alnilam

Alnilam lights up NGC 1990.
Photograph by Glen Youman
Observation data
Epoch J2000      Equinox J2000
Constellation Orion
Right ascension 05h 36m 12.8s
Declination −01° 12′ 06.9″
Apparent magnitude (V) 1.70
Characteristics
Spectral type B0 Ia
U−B color index −1.03
B−V color index −0.19
Variable type Alp Cyg
Astrometry
Radial velocity (Rv) 25.9 km/s
Proper motion (μ) RA: 1.49 mas/yr
Dec.: −1.06 mas/yr
Parallax (π) 2.43 ± 0.91 mas
Distance approx. 1,300 ly
(approx. 400 pc)
Absolute magnitude (MV) −6.4
Details
Radius 24R
Luminosity 275,000L
Surface gravity (log g) 2.9
Temperature 27,000K
Rotational velocity (v sin i) 91 km/s
Other designations
Alnilam, ε Ori, 46 Orionis, 112 G. Orionis, HR 1903, BD -01°969, HD 37128, SAO 132346, FK5 210, HIP 26311, TD1 4963, 参宿二.
Database references
SIMBAD data

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Alnilam, which is released under the Creative Commons Attribution-Share-Alike License 3.0