TT Cygni

TT Cygni

A light curve for TT Cygni, plotted from Hipparcos data
Observation data
Epoch J2000.0      Equinox ICRS
Constellation Cygnus
Right ascension 19h 40m 57.01599s
Declination +32° 37′ 05.7555″
Apparent magnitude (V) 7.26 - 8.0
Characteristics
Evolutionary stage AGB
Spectral type C5,4e(N3e)
B−V color index +2.917±0.073
Variable type SRb
Astrometry
Radial velocity (Rv)−49.0±3.1 km/s
Proper motion (μ) RA: −5.178 mas/yr
Dec.: −1.832 mas/yr
Parallax (π)1.4908±0.0368 mas
Distance2,190 ± 50 ly
(670 ± 20 pc)
Absolute magnitude (MV)−1.297 (var.)
Details
Mass3.4 M☉
Radius166 R☉
Luminosity2,735 L☉
Surface gravity (log g)−0.4 cgs
Temperature3,200 K
Metallicity [Fe/H]−9.49 dex
Other designations
TT Cyg, BD+32°3522, HD 186047, HIP 96836, SAO 68688
Database references
SIMBADdata

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. 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. It was listed with its variable star designation, TT Cygni, in Annie Jump Cannon's 1907 work Second Catalog of Variable Stars.

A thin spherical shell around the star, about half a light year across, was emitted 7,000 years ago. 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.

References

  1. ↑ "Hipparcos Tools Interactive Data Access". Hipparcos. ESA. Retrieved 8 December 2021.
  2. 1 2 3 4 5 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.
  3. 1 2 3 "TT Cygni". International Variable Star Index. AAVSO. Retrieved 2021-02-04.
  4. ↑ 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.
  5. 1 2 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.
  6. ↑ 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.
  7. ↑ 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.
  8. 1 2 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.
  9. ↑ 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.
  10. 1 2 3 4 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.
  11. ↑ "TT Cyg". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-02-03.
  12. ↑ 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.
  13. ↑ Cannon, Annie J. (1907). "Second catalogue of variable stars". Annals of Harvard College Observatory. 55: 1–94. Bibcode:1907AnHar..55....1C.
  14. ↑ 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.