Epsilon Normae

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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]
Spectral type B4 V + B4 V + B9 V[3]
U−B color index −0.54[2]
B−V color index −0.07[2]
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[1] mas
Distance 530 ± 20 ly
(163 ± 7 pc)
Absolute magnitude (MV) 0.06[5]
Period (P) 3.2617 d
Eccentricity (e) 0.13
Periastron epoch (T) 2438825.9310 JD
Argument of periastron (ω)
Semi-amplitude (K1)
122.5 km/s
Semi-amplitude (K2)
132.9 km/s
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

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]

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]


  1. ^ a b c d e f van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, Bibcode:2007A&A...474..653V, arXiv:0708.1752Freely accessible, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c d Johnson, H. L. (1966), "UBVRIJKL Photometry of the Bright Stars", Communications of the Lunar and Planetary Laboratory, 4, Bibcode:1966CoLPL...4...99J. 
  3. ^ a b c d Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, Bibcode:2008MNRAS.389..869E, arXiv:0806.2878Freely accessible, doi:10.1111/j.1365-2966.2008.13596.x. 
  4. ^ de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, Bibcode:2012A&A...546A..61D, arXiv:1208.3048Freely accessible, doi:10.1051/0004-6361/201219219, A61. 
  5. ^ a b Gontcharov, G. A. (November 2012), "Spatial distribution and kinematics of OB stars", Astronomy Letters, 38 (11): 694−706, Bibcode:2012AstL...38..694G, arXiv:1606.09028Freely accessible, doi:10.1134/S1063773712110035. 
  6. ^ a b Pourbaix, D.; et al. (2004), "SB9: The Ninth Catalogue of Spectroscopic Binary Orbits", Astronomy & Astrophysics, 424: 727–732, Bibcode:2009yCat....102020P, doi:10.1051/0004-6361:20041213. 
  7. ^ a b c Tetzlaff, N.; et al. (January 2011), "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun", Monthly Notices of the Royal Astronomical Society, 410 (1): 190–200, Bibcode:2011MNRAS.410..190T, arXiv:1007.4883Freely accessible, doi:10.1111/j.1365-2966.2010.17434.x. 
  8. ^ a b McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, Bibcode:2012MNRAS.427..343M, arXiv:1208.2037Freely accessible, doi:10.1111/j.1365-2966.2012.21873.x. 
  9. ^ "eps Nor". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-08-12. 
  10. ^ Chini, R.; et al. (2012), "A spectroscopic survey on the multiplicity of high-mass stars", Monthly Notices of the Royal Astronomical Society, 424 (3): 1925, Bibcode:2012MNRAS.424.1925C, arXiv:1205.5238Freely accessible, doi:10.1111/j.1365-2966.2012.21317.x.