T Cygni
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 | ±0.003 1.294[2] |
Variable type | Lb:[5] |
Astrometry | |
Radial velocity (Rv) | ±0.3 −23.9[6] km/s |
Proper motion (μ) | RA: +39.637[1] mas/yr Dec.: +8.068[1] mas/yr |
Parallax (π) | 8.4327 ± 0.1348[1] mas |
Distance | 387 ± 6 ly (119 ± 2 pc) |
Absolute magnitude (MV) | −0.74[2] |
Details | |
T Cyg A | |
Radius | 27[7] R☉ |
Luminosity | 333.48[2] L☉ |
Surface gravity (log g) | 2.12[8] cgs |
Temperature | 4,190[8] K |
Metallicity [Fe/H] | −0.12[8] dex |
Other designations | |
Database references | |
SIMBAD | data |
T Cygni is a binary star[10] 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 mas, 8.4[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]
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 measured angular diameter of this star, after correction for limb darkening, is ±0.02 mas. 2.11[11] At the estimated distance of this star, this yields a physical size of about 27 times the Sun's radius.[7] It is radiating 333[2] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,190 K.[8]
The secondary companion, component B, is a magnitude 10.03 star located at an angular separation of ″ along a 8.10position angle of 120°, as of 2012. In 1877 it was separated by with nearly the same position angle (121°). 10.0″[3]
References
- 1 2 3 4 5 6 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.
- 1 2 3 4 5 6 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.
- 1 2 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.
- 1 2 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.
- 1 2 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.
- 1 2 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.
- 1 2 Lang, Kenneth R. (2006). "Astrophysical formulae". Astronomy and astrophysics library. 1 (3 ed.). Birkhäuser. ISBN 3-540-29692-1.
. The radius (R*) is given by:
- 1 2 3 4 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.
- ↑ Richichi, A.; et al. (February 2005). "CHARM2: An updated Catalog of High Angular Resolution Measurements". Astronomy and Astrophysics. 431 (2): 773–777. Bibcode:2005A&A...431..773R. doi:10.1051/0004-6361:20042039.