TT Cygni
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Cygnus |
| Right ascension | 19h 40m 57.01599s[2] |
| Declination | +32° 37′ 05.7555″[2] |
| Apparent magnitude (V) | 7.26 - 8.0[3] |
| Characteristics | |
| Evolutionary stage | AGB[4] |
| Spectral type | C5,4e(N3e)[3] |
| B−V color index | +2.917±0.073[5] |
| Variable type | SRb[6] |
| Astrometry | |
| Radial velocity (Rv) | −49.0±3.1[5] km/s |
| Proper motion (μ) | RA: −5.178[2] mas/yr Dec.: −1.832[2] mas/yr |
| Parallax (π) | 1.4908±0.0368 mas[2] |
| Distance | 2,190 ± 50 ly (670 ± 20 pc) |
| Absolute magnitude (MV) | −1.297 (var.)[7] |
| Details | |
| Mass | 3.4[8] M☉ |
| Radius | 166[9] R☉ |
| Luminosity | 2,735[10] L☉ |
| Surface gravity (log g) | −0.4[10] cgs |
| Temperature | 3,200[10] K |
| Metallicity [Fe/H] | −9.49[8] dex |
| Other designations | |
| TT Cyg, BD+32°3522, HD 186047, HIP 96836, SAO 68688[11] | |
| Database references | |
| SIMBAD | data |
TT Cygni is a carbon star located 561 parsecs (1,830 ly) away in the northern constellation of Cygnus. It is classified as a semiregular variable of subtype SRb that ranges in brightness from magnitude 7.26 down to 8.0 with a period of 118 days.[3] This object is called a carbon star because it has a high ratio of carbon to oxygen in its surface layers. The carbon was produced by helium fusion, dredged up from inside the star by deep convection triggered by a flash from the helium shell.
In 1898 it was announced that Louisa Dennison Wells had discovered that the star, then known as BD +32°3522, is a variable star.[12] It was listed with its variable star designation, TT Cygni, in Annie Jump Cannon's 1907 work Second Catalog of Variable Stars.[13]
A thin spherical shell around the star, about half a light year across, was emitted 7,000 years ago.[14] It was first detected from its carbon monoxide emission and has a mass around four thousandths M☉, of which about a tenth is dust. The dust is thought to be mostly amorphous carbon.[10]
References
[edit]- ^ "Hipparcos Tools Interactive Data Access". Hipparcos. ESA. Retrieved 8 December 2021.
- ^ 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. Gaia DR2 record for this source at VizieR.
- ^ a b c "TT Cygni". International Variable Star Index. AAVSO. Retrieved 2021-02-04.
- ^ Maercker, M.; De Beck, E.; Khouri, T.; Vlemmings, W. H. T.; Gustafsson, J.; Olofsson, H.; Tafoya, D.; Kerschbaum, F.; Lindqvist, M. (2024). "Probing the dynamical and kinematical structures of detached shells around AGB stars". Astronomy and Astrophysics. 687: A112. arXiv:2405.01222. Bibcode:2024A&A...687A.112M. doi:10.1051/0004-6361/202449643.
- ^ a b 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.
- ^ Samus, N. N.; et al. (2017). "General Catalogue of Variable Stars". Astronomy Reports. 5.1. 61 (1): 80–88. Bibcode:2017ARep...61...80S. doi:10.1134/S1063772917010085. S2CID 125853869.
- ^ Gontcharov, G. A. (2011). "The red giant branch in the Tycho-2 catalogue". Astronomy Letters. 37 (10): 707–717. arXiv:1607.00557. Bibcode:2011AstL...37..707G. doi:10.1134/S1063773711090040. S2CID 119272127.
- ^ a b Khalatyan, A.; Anders, F.; Chiappini, C.; Queiroz, A. B. A.; Nepal, S.; Dal Ponte, M.; Jordi, C.; Guiglion, G.; Valentini, M.; Torralba Elipe, G.; Steinmetz, M.; Pantaleoni-González, M.; Malhotra, S.; Jiménez-Arranz, Ó.; Enke, H.; Casamiquela, L.; Ardèvol, J. (2024). "Transferring spectroscopic stellar labels to 217 million Gaia DR3 XP stars with SHBoost". Astronomy and Astrophysics. 691: A98. arXiv:2407.06963. Bibcode:2024A&A...691A..98K. doi:10.1051/0004-6361/202451427.
- ^ McDonald, I.; Zijlstra, A. A.; Watson, R. A. (2017). "Fundamental parameters and infrared excesses of Tycho–Gaia stars". Monthly Notices of the Royal Astronomical Society. 471 (1): 770–791. arXiv:1706.02208. Bibcode:2017MNRAS.471..770M. doi:10.1093/mnras/stx1433.
- ^ a b c d Groenewegen, M. A. T. (2012). "An extension of the DUSTY radiative transfer code and an application to OH 26.5 and TT Cygni". Astronomy and Astrophysics. 543: A36. Bibcode:2012A&A...543A..36G. doi:10.1051/0004-6361/201218965.
- ^ "TT Cyg". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-02-03.
- ^ Pickering, E. C.; Bailey, S. I.; Fleming, W. P.; Leland, E. F.; Wells, L. D. (March 1898). "Variable star clusters. New variable stars". Astrophysical Journal. 7: 208–211. Bibcode:1898ApJ.....7..208P. doi:10.1086/140457.
- ^ Cannon, Annie J. (1907). "Second catalogue of variable stars". Annals of Harvard College Observatory. 55: 1–94. Bibcode:1907AnHar..55....1C.
- ^ Olofsson, H.; et al. (January 2000). "A high-resolution study of episodic mass loss from the carbon star TT Cygni". Astronomy and Astrophysics. 353: 583–597. Bibcode:2000A&A...353..583O.