42 Orionis

42 Orionis, also known as c Orionis or c Ori, is a class B1V^[3] (blue main-sequence) star in the constellation Orion. Its apparent magnitude is 4.59^[2] and it is approximately 900 light years away based on parallax.^[1]

42 Orionis

Location of 42 Orionis (marked red)
Observation data Epoch J2000      Equinox J2000
Constellation	Orion
Right ascension	05h 35m 23.16427s[1]
Declination	−04° 50′ 18.0881″[1]
Apparent magnitude (V)	4.59[2]
Characteristics
Spectral type	B1V[3]
U−B color index	−0.94[2]
B−V color index	−0.19[2]
Astrometry
Radial velocity (Rv)	+28.40[4] km/s
Proper motion (μ)	RA: +4.52[1] mas/yr Dec.: −7.11[1] mas/yr
Parallax (π)	3.69±1.20 mas[1]
Distance	approx. 900 ly (approx. 270 pc)
Details
Mass	12.0[5] M☉
Radius	7.0[6] R☉
Luminosity	10,737[7] L☉
Surface gravity (log g)	3.82[6] cgs
Temperature	25,400[7] K
Rotational velocity (v sin i)	20[8] km/s
Age	2.6[5] Myr
Other designations
c Orionis, BD−04°1185, CCDM J05354-0450AB, GC 6934, HIP 26237, HR 1892, HD 37018, NSV 2318, SAO 132320, WDS J05354-0450AB
Database references
SIMBAD	data

42 Ori is the bright star at the centre of NGC 1977.

The primary star, Aa, has one spectroscopic companion Ab of magnitude 6.3 and separation 0.16", and a more distant companion B of 7.5 magnitude at 1.6" separation.^[9][10]

42 Orionis is surrounded by NGC 1977 one of a smaller fainter group of named nebulae just north of the Orion Nebula. 42 Ori is the star which excites and illuminates NGC 1977.