Epsilon Normae

Epsilon Normae
Observation data; Epoch J2000.0 Equinox J2000.0 (ICRS)
Constellation	Norma
	A
Right ascension	16h 27m 11.03611s
Declination	−47° 33′ 17.2226″
Apparent magnitude (V)	4.47
	B
Right ascension	16h 27m 10.06643s
Declination	−47° 32′ 56.6763″
Apparent magnitude (V)	6.13
Characteristics
Spectral type	B4 V + B4 V + B9 V
U−B color index	−0.54
B−V color index	−0.07
Astrometry
A
Radial velocity (Rv)	−12.5±2.7 km/s
Proper motion (μ)	RA: −13.68±0.27 mas/yr ; Dec.: −19.89±0.20 mas/yr
Parallax (π)	6.15±0.28 mas
Distance	530 ± 20 ly ; (163 ± 7 pc)
Absolute magnitude (MV)	+0.06
B
Radial velocity (Rv)	−6.67±0.83 km/s
Proper motion (μ)	RA: −10.393 mas/yr ; Dec.: −20.277 mas/yr
Parallax (π)	5.4467±0.0299 mas
Distance	599 ± 3 ly ; (184 ± 1 pc)
Orbit
Primary	Aa
Companion	Ab
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
Aa
Mass	7.7 M☉
Ab
Mass	4.5 M☉
B
Mass	2.3 M☉
Radius	2.4 R☉
Luminosity	74 L☉
Surface gravity (log g)	4.00 cgs
Temperature	11,104 K
Other designations
	ε Nor, CD−47°10765, HD 147971, HIP 80582, HR 6115, SAO 226773, WDS J16272-4733A
	B: HD 147970, HIP 80579
Database references
SIMBAD	data
	B

Epsilon Normae, Latinised from ε Normae, is a blue-white hued triple star^[5] 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.^[7]

The inner pair form a double-lined spectroscopic binary^[12] system with an orbital period of 3.26 days and an eccentricity of 0.13.^[8] Both stars appear to be similar B-type main-sequence stars with stellar classifications of B4 V.^[5]

The third component, at an angular separation of 22.8 arc seconds from the inner pair, is HD 147970. It is most likely is a smaller B-type main sequence star of spectral type B9V.^[5]

References

^ ^a ^b ^c ^d ^e ^f van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600.
^ ^a ^b ^c ^d Johnson, H. L. (1966), "UBVRIJKL Photometry of the Bright Stars", Communications of the Lunar and Planetary Laboratory, 4: 99, Bibcode:1966CoLPL...4...99J.
^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
^ Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355. Bibcode:2000A&A...355L..27H.
^ ^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, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
^ 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, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, S2CID 59451347, A61.
^ ^a ^b Gontcharov, G. A. (November 2012), "Spatial distribution and kinematics of OB stars", Astronomy Letters, 38 (11): 694–706, arXiv:1606.09028, Bibcode:2012AstL...38..694G, doi:10.1134/S1063773712110035, S2CID 119108982.
^ ^a ^b Pourbaix, D.; et al. (2004), "SB9: The Ninth Catalogue of Spectroscopic Binary Orbits", Astronomy & Astrophysics, 424: 727–732, arXiv:astro-ph/0406573, Bibcode:2004A&A...424..727P, doi:10.1051/0004-6361:20041213, S2CID 119387088.
^ ^a ^b ^c Tokovinin, Andrei (2018). "The Updated Multiple Star Catalog". The Astrophysical Journal Supplement Series. 235 (1): 6. arXiv:1712.04750. Bibcode:2018ApJS..235....6T. doi:10.3847/1538-4365/aaa1a5.
^ "eps Nor". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-08-12.
^ "HD 147970". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2025-05-28.
^ 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, arXiv:1205.5238, Bibcode:2012MNRAS.424.1925C, doi:10.1111/j.1365-2966.2012.21317.x, S2CID 119120749.

[vanLeeuwen2007-1] ^ ^a ^b ^c ^d ^e ^f van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600.

[Johnson1966-2] Johnson, H. L. (1966), "UBVRIJKL Photometry of the Bright Stars", Communications of the Lunar and Planetary Laboratory, 4: 99, Bibcode:1966CoLPL...4...99J.

[dr3b-3] ^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.

[tycho2-4] Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355. Bibcode:2000A&A...355L..27H.

[Eggleton2008-5] 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, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.

[deBruijne2012-6] Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, S2CID 59451347, A61.

[Gontcharov2012-7] Gontcharov, G. A. (November 2012), "Spatial distribution and kinematics of OB stars", Astronomy Letters, 38 (11): 694–706, arXiv:1606.09028, Bibcode:2012AstL...38..694G, doi:10.1134/S1063773712110035, S2CID 119108982.

[Pourbaix2004-8] Pourbaix, D.; et al. (2004), "SB9: The Ninth Catalogue of Spectroscopic Binary Orbits", Astronomy & Astrophysics, 424: 727–732, arXiv:astro-ph/0406573, Bibcode:2004A&A...424..727P, doi:10.1051/0004-6361:20041213, S2CID 119387088.

[msc-9] Tokovinin, Andrei (2018). "The Updated Multiple Star Catalog". The Astrophysical Journal Supplement Series. 235 (1): 6. arXiv:1712.04750. Bibcode:2018ApJS..235....6T. doi:10.3847/1538-4365/aaa1a5.

[SIMBAD-10] "eps Nor". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-08-12.

[SIMBADB-11] "HD 147970". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2025-05-28.

[chini2012-12] 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, arXiv:1205.5238, Bibcode:2012MNRAS.424.1925C, doi:10.1111/j.1365-2966.2012.21317.x, S2CID 119120749.

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Epsilon Normae

References

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