Epsilon Normae
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Norma |
| A | |
| Right ascension | 16h 27m 11.03611s[1] |
| Declination | −47° 33′ 17.2226″[1] |
| Apparent magnitude (V) | 4.47[2] |
| B | |
| Right ascension | 16h 27m 10.06643s[3] |
| Declination | −47° 32′ 56.6763″[3] |
| Apparent magnitude (V) | 6.13[4] |
| Characteristics | |
| Spectral type | B4 V + B4 V + B9 V[5] |
| U−B color index | −0.54[2] |
| B−V color index | −0.07[2] |
| Astrometry | |
| A | |
| Radial velocity (Rv) | −12.5±2.7[6] 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[7] |
| B | |
| Radial velocity (Rv) | −6.67±0.83[3] km/s |
| Proper motion (μ) | RA: −10.393[3] mas/yr Dec.: −20.277[3] mas/yr |
| Parallax (π) | 5.4467 ± 0.0299 mas[3] |
| Distance | 599 ± 3 ly (184 ± 1 pc) |
| Orbit[8] | |
| 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[9] M☉ |
| Ab | |
| Mass | 4.5[9] M☉ |
| B | |
| Mass | 2.3[9] M☉ |
| Radius | 2.4[3] R☉ |
| Luminosity | 74[3] L☉ |
| Surface gravity (log g) | 4.00[3] cgs |
| Temperature | 11,104[3] K |
| Other designations | |
| ε Nor, CD−47°10765, HD 147971, HIP 80582, HR 6115, SAO 226773, WDS J16272-4733A[10] | |
| B: HD 147970, HIP 80579[11] | |
| 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
[edit]- ^ 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.
