51 Orionis

Location of 51 Orionis (circled)
Observation data Epoch J2000       Equinox J2000
Constellation	Orion
Right ascension	05h 42m 28.63240s [1]
Declination	+01° 28′ 28.6714″ [1]
Apparent magnitude (V)	4.90 [2]
Characteristics
Spectral type	K1III [3]
U−B color index	+1.06 [2]
B−V color index	+1.17 [2]
Astrometry
Radial velocity (Rv)	+87.55 [4] km/s
Proper motion (μ)	RA: −54.741 [1]  mas/ yr Dec.: −14.732 [1]  mas/ yr
Parallax (π)	10.9178 ± 0.2225  mas [1]
Distance	299 ± 6  ly (92 ± 2  pc)
Absolute magnitude (MV)	0.13 [5]
Details
Mass	1.11 [5]  M☉
Radius	19.3+0.4 −1.0 [1]  R☉
Luminosity	132±3 [1]  L☉
Surface gravity (log g)	2.24 [6]  cgs
Temperature	4,458+92 −51 [1]  K
Metallicity [Fe/H]	−0.45 [6]  dex
Rotational velocity (v sin i)	1.1 [7] km/s
Age	4.06 [8]  Gyr
Other designations
b Ori, 51 Ori, BD+01°1105, FK5 2427, GC 7136, HD 37984, HIP 26885, HR 1963, SAO 113056 [9]
Database references
SIMBAD	data

51 Orionis is a single ^[10] star in the equatorial constellation of Orion. ^[9] It has the Bayer designation b Orionis, while 51 Orionis is the Flamsteed designation. This object is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 4.90. ^[2] It is located approximately 299  light-years away from the Sun based on parallax, ^[1] and is drifting further away with a radial velocity of +88 km/s. ^[4]

This is an aging giant star with a stellar classification of K1III, ^[3] having exhausted the supply of hydrogen at its core and expanded to 19 times the Sun's radius. ^[1] It is four ^[8] billion years old with 1.11 ^[5] times the mass of the Sun. The star is radiating 132 ^[1] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,458 K. ^[1]

References