Epsilon Normae

Epsilon Normae, Latinised from ε Normae, is a blue-white hued triple star^[3] system in the southern constellation of Norma. It has an apparent visual magnitude of 4.47,^[2] which is bright enough to be seen with the naked eye. Based upon an annual parallax shift of 6.15 mas as seen from Earth,^[1] the system is located around 530 light years distant from the Sun. At that distance, the visual magnitude is diminished by an extinction factor of 0.21 due to interstellar dust.^[5]

Epsilon Normae

Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Norma
Right ascension	16h 27m 11.03611s[1]
Declination	−47° 33′ 17.2226″[1]
Apparent magnitude (V)	4.47[2]
Characteristics
Spectral type	B4 V + B4 V + B9 V[3]
U−B color index	−0.54[2]
B−V color index	−0.07[2]
Astrometry
Radial velocity (Rv)	−12.5±2.7[4] km/s
Proper motion (μ)	RA: −13.68±0.27[1] mas/yr Dec.: −19.89±0.20[1] mas/yr
Parallax (π)	6.15±0.28 mas[1]
Distance	530 ± 20 ly (163 ± 7 pc)
Absolute magnitude (MV)	0.06[5]
Orbit[6]
Period (P)	3.2617 d
Eccentricity (e)	0.13
Periastron epoch (T)	2438825.9310 JD
Argument of periastron (ω) (secondary)	271.5°
Semi-amplitude (K1) (primary)	122.5 km/s
Semi-amplitude (K2) (secondary)	132.9 km/s
Details
Mass	6.4±0.2[7] M☉
Luminosity	474[8] L☉
Temperature	10,888[8] K
Age	50.1±14.0[7] Myr
Other designations
ε Nor, CD−47° 10765, HD 147971, HIP 80582, HR 6115, SAO 226773, WDS J16272-4733A[9]
Database references
SIMBAD	data

The inner pair form a double-lined spectroscopic binary^[10] system with an orbital period of 3.26 days and an eccentricity of 0.13.^[6] Both stars appear to be similar B-type main-sequence stars with stellar classifications of B4 V.^[3] The third component has an angular separation of 22.8 arc seconds from the inner pair, and most likely is a smaller B-type main sequence star of spectral type B9V.^[3] The system is relatively young, with an estimated age of around 50 million years.^[7]