T Cygni

Not to be confused with Tau Cygni.
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 1.294±0.003[2]
Variable type Lb:[5]
Astrometry
Radial velocity (Rv)−23.9±0.3[6] km/s
Proper motion (μ) RA: +39.637[1] mas/yr
Dec.: +8.068[1] mas/yr
Parallax (π)8.4327 ± 0.1348 mas[1]
Distance387 ± 6 ly
(119 ± 2 pc)
Absolute magnitude (MV)−0.74[2]
Details
A
Radius28.19+0.67
−0.86[1] R☉
Luminosity241.4±4.5[1] L☉
Surface gravity (log g)2.12[7] cgs
Temperature4,285+50
−67[1] K
Metallicity [Fe/H]−0.12[7] dex
Other designations
T Cyg, BD+33° 4028, HD 198134, HIP 102571, HR 7956, SAO 70499, WDS J20472+3422A[8]
Database references
SIMBADdata

T Cygni is a binary star[9] 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 8.4 mas,[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 star has expanded to 28 times the radius of the Sun.[1] It is radiating 241 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,285 K.[1]

The secondary companion, component B, is a magnitude 10.03 star located at an angular separation of 8.10″ along a position angle of 120°, as of 2012. In 1877 it was separated by 10.0″ with nearly the same position angle (121°).[3]

  1. ^ a b c d e f g h i j k Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference WDSC2014 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Herbig1955 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference gcvs was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference Gontcharov2006 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference McWilliam1990 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).