T Cygni is a binary star[9] system in the northern constellation of Cygnus. It is a faint system but visible to the naked eye with a combined apparent visual magnitude of 4.93.[2] Based upon an annual Parallax shift of 8.4 mas,[1] it is located 387 light years away. It is moving closer to the Earth with a heliocentric radial velocity of −24 km/s.[6]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cygnus |
| Right ascension | 20h 47m 10.75239s[1] |
| Declination | +34° 22′ 26.8374″[1] |
| Apparent magnitude (V) | 4.93[2] + 10.03[3] |
| Characteristics | |
| Spectral type | K3 III[4] |
| B−V color index | 1.294±0.003[2] |
| Variable type | Lb:[5] |
| Astrometry | |
| Radial velocity (Rv) | −23.9±0.3[6] km/s |
| Proper motion (μ) | RA: +39.637[1] mas/yr Dec.: +8.068[1] mas/yr |
| Parallax (π) | 8.4327 ± 0.1348 mas[1] |
| Distance | 387 ± 6 ly (119 ± 2 pc) |
| Absolute magnitude (MV) | −0.74[2] |
| Details | |
| A | |
| Radius | 28.19+0.67 −0.86[1] R☉ |
| Luminosity | 241.4±4.5[1] L☉ |
| Surface gravity (log g) | 2.12[7] cgs |
| Temperature | 4,285+50 −67[1] K |
| Metallicity [Fe/H] | −0.12[7] dex |
| Other designations | |
| Database references | |
| SIMBAD | data |
The primary, component A, is a variable star, most likely of the slow irregular type, which ranges in magnitude from 4.91 down to 4.96.[5] It is a giant star with a stellar classification of K3 III,[4] which indicates it has exhausted the hydrogen at its core and evolved away from the main sequence. The star has expanded to 28 times the radius of the Sun.[1] It is radiating 241 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,285 K.[1]
The secondary companion, component B, is a magnitude 10.03 star located at an angular separation of 8.10″ along a position angle of 120°, as of 2012. In 1877 it was separated by 10.0″ with nearly the same position angle (121°).[3]
References
edit- ^ a b c d e f g h i j k 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. Gaia DR2 record for this source at VizieR.
- ^ a b c d 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 Mason, B. D.; et al. (2014). "The Washington Visual Double Star Catalog". The Astronomical Journal. 122 (6): 3466–3471. Bibcode:2001AJ....122.3466M. doi:10.1086/323920.
- ^ a b Herbig, George H.; Spalding, John F. Jr. (January 1955). "Axial Rotation and Line Broadening in Stars of Spectral Types F0-K5". Astrophysical Journal. 121: 118. Bibcode:1955ApJ...121..118H. doi:10.1086/145969.
- ^ a b Samus', N. N; Kazarovets, E. V; Durlevich, O. V; Kireeva, N. N; Pastukhova, E. N (2017). "General catalogue of variable stars: Version GCVS 5.1". Astronomy Reports. 61 (1): 80. Bibcode:2017ARep...61...80S. doi:10.1134/S1063772917010085. S2CID 125853869.
- ^ a b Gontcharov, G. A. (November 2006). "Pulkovo Compilation of Radial Velocities for 35495 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.
- ^ a b McWilliam, Andrew (December 1990). "High-resolution spectroscopic survey of 671 GK giants. I - Stellar atmosphere parameters and abundances". Astrophysical Journal Supplement Series. 74: 1075–1128. Bibcode:1990ApJS...74.1075M. doi:10.1086/191527.
- ^ "T Cyg". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 1 September 2018.
- ^ Eggleton, P. P.; Tokovinin, A. A. (2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society. 389 (2): 869. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x. S2CID 14878976.