47 Cygni
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cygnus |
| Right ascension | 20h 33m 54.18821s[1] |
| Declination | +35° 15′ 03.02810″[1] |
| Apparent magnitude (V) | 4.61[2] (4.84 + 7.30)[3] |
| Characteristics | |
| Spectral type | K6: Ib + B2.5:[2] |
| B−V color index | 1.593±0.023[4] |
| Variable type | Lc[5] |
| Astrometry | |
| Radial velocity (Rv) | −4.6±0.3[6] km/s |
| Proper motion (μ) | RA: −3.746[1] mas/yr Dec.: −3.408[1] mas/yr |
| Parallax (π) | 0.7605 ± 0.2285 mas[1] |
| Distance | approx. 4,000 ly (approx. 1,300 pc) |
| Absolute magnitude (MV) | −4.1 (−4 + −1.5)[2] |
| Orbit[7] | |
| Period (P) | 1117±11 d |
| Eccentricity (e) | 0.00 (assumed) |
| Periastron epoch (T) | 2,447,088±10 JD |
| Semi-amplitude (K1) (primary) | 2.0±0.1 km/s |
| Details | |
| 47 Cyg Aa | |
| Mass | 12.1±0.2[8] M☉ |
| Surface gravity (log g) | 1.23[9] cgs |
| Temperature | 4,217[9] K |
| Metallicity [Fe/H] | 0.13[9] dex |
| Age | 17.6±0.6[8] Myr |
| 47 Cyg Ab | |
| Mass | 0.57[10] M☉ |
| 47 Cyg B | |
| Mass | 10.96[10] M☉ |
| Other designations | |
| Database references | |
| SIMBAD | data |
47 Cygni is a triple star[3][12] system in the northern constellation of Cygnus, and is located around 4,000 light years from the Earth. It is visible to the naked eye with a combined apparent visual magnitude of 4.61.[2] The system is moving closer to the Earth with a heliocentric radial velocity of −4.6 km/s.[6]
The dual nature of this system was recognized by Annie Cannon in 1912, and she assigned the pair separate Henry Draper Catalogue identifiers.[7] They orbit each other with a period of around 143.69 yr.[10] The primary component is itself a spectroscopic binary in a near circular orbit with a period of around 3.06 yr. The a sin i value for the primary is 30.8 ± 1.6 Gm (0.206 ± 0.011 AU), where a is the semimajor axis and i is the orbital inclination. It has been repeatedly resolved by speckle interferometery since 1973. Radio emission was detected from this system in 1985/86.[7]
The supergiant primary is a slow irregular variable with an amplitude of about 0.1 magnitudes.[5] Its close companion has 57% of the mass of the Sun.[10] The secondary is a hot B-type main-sequence star, but still 2.5 magnitudes fainter than the primary.[3]
References
- ^ a b c d e Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051.
- ^ a b c d Ginestet, N.; Carquillat, J. M. (December 2002), "Spectral Classification of the Hot Components of a Large Sample of Stars with Composite Spectra, and Implication for the Absolute Magnitudes of the Cool Supergiant Components", The Astrophysical Journal Supplement Series, 143 (2): 513–537, Bibcode:2002ApJS..143..513G, doi:10.1086/342942.
- ^ a b c 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.
- ^ 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.
- ^ a b Samus, N. N.; Durlevich, O. V.; et al. (2009), "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)", VizieR On-line Data Catalog: B/gcvs. Originally Published in: 2009yCat....102025S, 1, Bibcode:2009yCat....102025S.
- ^ a b 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.
- ^ a b c Griffin, R. F. (June 1992), "Spectroscopic binary orbits from photoelectric radial velocities. Paper 104: 47 Cygni", The Observatory, 112: 111–120, Bibcode:1992Obs...112..111G.
- ^ a b Tetzlaff, N.; Neuhäuser, R.; Hohle, M. M. (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, arXiv:1007.4883, Bibcode:2011MNRAS.410..190T, doi:10.1111/j.1365-2966.2010.17434.x.
- ^ a b c Soubiran, Caroline; et al. (2016), "The PASTEL catalogue: 2016 version", Astronomy and Astrophysics, 591: A118, arXiv:1605.07384, Bibcode:2016A&A...591A.118S, doi:10.1051/0004-6361/201628497.
- ^ a b c d Tokovinin, A. (2008), "Comparative statistics and origin of triple and quadruple stars", Monthly Notices of the Royal Astronomical Society, 389 (2): 925–938, arXiv:0806.3263, Bibcode:2008MNRAS.389..925T, doi:10.1111/j.1365-2966.2008.13613.x.
- ^ "47 Cyg". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-01-14.
- ^ Mason, Brian D.; et al. (2001), "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog", The Astronomical Journal, 122 (6): 3466, Bibcode:2001AJ....122.3466M, doi:10.1086/323920.