Epsilon Equulei
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Equuleus |
| Right ascension | 20h 59m 04.47539s[1] |
| Declination | 04° 17′ 36.5211″[1] |
| Apparent magnitude (V) | 5.23[2] (5.96 / 6.31)[3] |
| Characteristics | |
| Spectral type | F5(V) + F6(V)[4] |
| U−B color index | +0.00[5] |
| B−V color index | +0.47[5] |
| Astrometry | |
| Radial velocity (Rv) | 8.20 ± 0.2[6] km/s |
| Proper motion (μ) | RA: -115.75[1] mas/yr Dec.: -151.70[1] mas/yr |
| Parallax (π) | 18.49 ± 1.35 mas[1] |
| Distance | 180 ± 10 ly (54 ± 4 pc) |
| Absolute magnitude (MV) | +1.65[7] |
| Orbit[3] | |
| Period (P) | 101.485 yr |
| Semi-major axis (a) | 0.6474″ |
| Eccentricity (e) | 0.705 |
| Inclination (i) | 92.17° |
| Longitude of the node (Ω) | 105.15° |
| Periastron epoch (T) | 1920.37 |
| Argument of periastron (ω) (secondary) | 340.19° |
| Details | |
| A | |
| Mass | 1.74[8] M☉ |
| Surface gravity (log g) | 3.87[9] cgs |
| Temperature | 6,223[9] K |
| B | |
| Mass | 1.53[8] M☉ |
| Surface gravity (log g) | 4.29[9] cgs |
| Temperature | 6,399[9] K |
| Age | 1.5[10] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Epsilon Equulei, Latinized from ε Equulei, is a star system of apparent magnitude +5.23[2] in the constellation of Equuleus. It is located 180 light years away from the Solar System, based on its parallax.[1]
Star system
[edit]Two stars make up the brighter part of the Epsilon Equulei star system. They are called Epsilon Equulei A and B and are main-sequence stars of spectral type of F5 and F6, respectively.[4] The orbital period of this binary is about 101.5 years. Although the average separation between the two stars is about 0.64″, the orbit is remarkably eccentric, at 0.705. The two stars passed their periastron in 1920.[3] Finally, it is thought that Epsilon Equulei A may be, in turn, a spectroscopic binary. The orbital period of the latter would be 2.03133 days.[11]
Approximately 10 arcseconds away from A and B is Epsilon Equulei C (HIP 103571), with an apparent magnitude of 7.35. It is another F-type main-sequence stars, and based on its similar distance and proper motion to A and B, it is assumed to be associated.[12]
The Epsilon Equulei system is thought to be approximately 1.5 billion years old.[13]
References
[edit]- ^ a b c d e f van Leeuwen, F.; et al. (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 "* eps Equ". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 8 July 2017.
- ^ a b c "Sixth Catalog of Orbits of Visual Binary Stars". United States Naval Observatory. Archived from the original on 1 August 2017. Retrieved 8 July 2017.
- ^ a b Beavers, W. I.; Cook, D. B. (1980). "Scanner studies of composite spectra. I - Dwarfs". The Astrophysical Journal Supplement Series. 44: 489. Bibcode:1980ApJS...44..489B. doi:10.1086/190702.
- ^ a b Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data: 0. Bibcode:1986EgUBV........0M.
- ^ Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. S2CID 119231169.
- ^ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
- ^ a b "Multiple Star Catalog". Archived from the original on 2018-11-29. Retrieved 2018-11-28.
- ^ a b c d Luck, R. Earle (2015). "Abundances in the Local Region. I. G and K Giants". The Astronomical Journal. 150 (3): 88. arXiv:1507.01466. Bibcode:2015AJ....150...88L. doi:10.1088/0004-6256/150/3/88. S2CID 118505114.
- ^ Casagrande, L.; Schönrich, R.; Asplund, M.; Cassisi, S.; Ramírez, I.; Meléndez, J.; Bensby, T.; Feltzing, S. (2011). "New constraints on the chemical evolution of the solar neighbourhood and Galactic disc(s). Improved astrophysical parameters for the Geneva-Copenhagen Survey". Astronomy and Astrophysics. 530: A138. arXiv:1103.4651. Bibcode:2011A&A...530A.138C. doi:10.1051/0004-6361/201016276. S2CID 56118016.
- ^ Abt, H. A.; Levy, S. G. (1976). "Multiplicity among solar-type stars". The Astrophysical Journal Supplement Series. 30: 273. Bibcode:1976ApJS...30..273A. doi:10.1086/190363.
- ^ "* eps Equ C". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 31 July 2017.
- ^ Casagrande, L.; Schönrich, R.; Asplund, M.; Cassisi, S.; Ramírez, I.; Meléndez, J.; Bensby, T.; Feltzing, S. (2011). "New constraints on the chemical evolution of the solar neighbourhood and Galactic disc(s). Improved astrophysical parameters for the Geneva-Copenhagen Survey". Astronomy & Astrophysics. 530: A138. arXiv:1103.4651. Bibcode:2011A&A...530A.138C. doi:10.1051/0004-6361/201016276. S2CID 56118016.
