Astronomy:Epsilon Normae
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Short description: Triple star system in the constellation Norma
| Observation data {{#ifeq:J2000.0|J2000.0 (ICRS)|Epoch J2000.0 Equinox J2000.0 (ICRS)| [[History:Epoch|Epoch J2000.0]] [[Astronomy:Equinox (celestial coordinates)|Equinox J2000.0}} | |
|---|---|
| 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[1] mas |
| 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[3] mas |
| 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 | |
| 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
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, doi:10.1051/0004-6361:20078357, Bibcode: 2007A&A...474..653V.
- ↑ 2.0 2.1 2.2 2.3 Johnson, H. L. (1966), "UBVRIJKL Photometry of the Bright Stars", Communications of the Lunar and Planetary Laboratory 4: 99, Bibcode: 1966CoLPL...4...99J.
- ↑ 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940 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. et al. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics 355. Bibcode: 2000A&A...355L..27H.
- ↑ 5.0 5.1 5.2 5.3 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, doi:10.1111/j.1365-2966.2008.13596.x, Bibcode: 2008MNRAS.389..869E.
- ↑ 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, doi:10.1051/0004-6361/201219219, A61, Bibcode: 2012A&A...546A..61D.
- ↑ 7.0 7.1 Gontcharov, G. A. (November 2012), "Spatial distribution and kinematics of OB stars", Astronomy Letters 38 (11): 694–706, doi:10.1134/S1063773712110035, Bibcode: 2012AstL...38..694G.
- ↑ 8.0 8.1 Pourbaix, D. et al. (2004), "SB9: The Ninth Catalogue of Spectroscopic Binary Orbits", Astronomy & Astrophysics 424: 727–732, doi:10.1051/0004-6361:20041213, Bibcode: 2004A&A...424..727P.
- ↑ 9.0 9.1 9.2 Tokovinin, Andrei (2018). "The Updated Multiple Star Catalog". The Astrophysical Journal Supplement Series 235 (1): 6. doi:10.3847/1538-4365/aaa1a5. Bibcode: 2018ApJS..235....6T.
- ↑ "eps Nor". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=eps+Nor.
- ↑ "HD 147970". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+147970.
- ↑ 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, doi:10.1111/j.1365-2966.2012.21317.x, Bibcode: 2012MNRAS.424.1925C.
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