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TT Cygni

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Star in the constellation Cygnus
TT Cygni

A light curve for TT Cygni, plotted from Hipparcos data
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Cygnus
Right ascension 19 40 57.01599
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
Radius166 R
Luminosity2,735 L
Surface gravity (log g)−0.4 cgs
Temperature3,200 K
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. ^ 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. ^ "TT Cygni", International Variable Star Index, AAVSO, retrieved 2021-02-04.
  4. ^ 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.
  5. 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.
  6. 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.
  7. 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.
  8. ^ 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.
  9. "TT Cyg". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-02-03.{{cite web}}: CS1 maint: postscript (link)
  10. 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. Retrieved 20 December 2024.
  11. Cannon, Annie J. (1907). "Second catalogue of variable stars". Annals of Harvard College Observatory. 55: 1–94. Bibcode:1907AnHar..55....1C. Retrieved 18 December 2024.
  12. 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.
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