TT Cygni

TT Cygni

A light curve for TT Cygni, plotted from Hipparcos data[1]
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
Spectral type C5,4e(N3e)[3]
B−V color index +2.917±0.073[4]
Variable type SRb[5]
Astrometry
Radial velocity (Rv)−49.0±3.1[4] 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]
Distance2,190 ± 50 ly
(670 ± 20 pc)
Absolute magnitude (MV)−1.297 (var.)[6]
Details
Radius166[7] R☉
Luminosity2,735[8] L☉
Surface gravity (log g)−0.4[8] cgs
Temperature3,200[8] K
Other designations
TT Cyg, BD+32°3522, HD 186047, HIP 96836, SAO 68688[9]
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.[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.

A thin spherical shell around the star, about half a light year across, was emitted 7,000 years ago.[10] 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.[8]

  1. ^ Cite error: The named reference HipDataAccess was invoked but never defined (see the help page).
  2. ^ a b c d e Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  3. ^ a b c Cite error: The named reference vsx was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Anderson_Francis_2012 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference Samus_et_al_2017 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference gontcharov2011 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference mcdonald2017 was invoked but never defined (see the help page).
  8. ^ a b c d Cite error: The named reference groenewegen2012 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Olofsson_et_al_2000 was invoked but never defined (see the help page).