47 Cygni

47 Cygni

A light curve for V2125 Cygni, plotted from Hipparcos data[1]
Observation data
Epoch J2000      Equinox J2000
Constellation Cygnus
Right ascension 20h 33m 54.18809s[2]
Declination +35° 15′ 03.0390″[2]
Apparent magnitude (V) 4.61[3] (4.84 + 7.30)[4]
Characteristics
Spectral type K6: Ib + B2.5:[3]
B−V color index 1.593±0.023[5]
Variable type Lc[6]
Astrometry
Radial velocity (Rv)−4.6±0.3[7] km/s
Proper motion (μ) RA: −6.12 mas/yr[2]
Dec.: −4.166 mas/yr[2]
Parallax (π)0.8792 ± 0.196 mas[2]
Distance4072+965
−773 ly
(1249+296
−237 pc)[8]
Absolute magnitude (MV)−4.1 (−4 + −1.5)[3]
Orbit[9]
Period (P)1117±11 d
Eccentricity (e)0.00 (assumed)
Periastron epoch (T)2,447,088±10 JD
Semi-amplitude (K1)
(primary)		2.0±0.1 km/s
Details
47 Cyg Aa
Mass12.1±0.2[10]
19.4±3.9[11] M☉
Radius601[12] R☉
Surface gravity (log g)1.23[13] cgs
Temperature4,217[13] K
Metallicity [Fe/H]0.13[13] dex
Age17.6±0.6[10] Myr
47 Cyg Ab
Mass0.57[14] M☉
47 Cyg B
Mass10.96[14] M☉
Other designations
47 Cyg, V2125 Cyg, BD+34°4079, GC 28630, HD 196093/196094, HIP 101474, HR 7866, SAO 70203, WDS J20339+3515, 2MASS J20335419+3515031[15]
Database references
SIMBADdata

47 Cygni is a triple star[4][16] system in the northern constellation of Cygnus, and is located around 4,000 light years from the Earth. It is visible to the naked eye with a combined apparent visual magnitude of 4.61.[3] The system is moving closer to the Earth with a heliocentric radial velocity of −4.6 km/s.[7]

The dual nature of this system was recognized by Annie Cannon in 1912, and she assigned the pair separate Henry Draper Catalogue identifiers.[9] They orbit each other with a period of around 143.69 yr.[14] The primary component is itself a spectroscopic binary in a near circular orbit with a period of around 3.06 yr. The a sin i value for the primary is 30.8 ± 1.6 Gm (0.206 ± 0.011 AU), where a is the semimajor axis and i is the orbital inclination. It has been repeatedly resolved by speckle interferometery since 1973. Radio emission was detected from this system in 1985/86.[9]

The supergiant primary is a slow irregular variable with an amplitude of about 0.1 magnitudes.[6] Its angular diameter has been measured at 4.472±0.017 milliarcseconds using interferometry by the Navy Precision Optical Interferometer.[17] At the distance of 1,249 parsecs,[8] it yield a radius of 601 R☉.[12] Its close companion has 57% of the mass of the Sun.[14] The secondary is a hot B-type main-sequence star, but still 2.5 magnitudes fainter than the primary.[4]

  1. ^ Cite error: The named reference CDS was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference DR3 was invoked but never defined (see the help page).
  3. ^ a b c d Cite error: The named reference Ginestet2002 was invoked but never defined (see the help page).
  4. ^ a b c Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference gcvs was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference Gontcharov2006 was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference bailer-jones was invoked but never defined (see the help page).
  9. ^ a b c Cite error: The named reference Griffin1992 was invoked but never defined (see the help page).
  10. ^ a b Cite error: The named reference Tetzlaff2011 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference kervella was invoked but never defined (see the help page).
  12. ^ a b Cite error: The named reference lang2006 was invoked but never defined (see the help page).
  13. ^ a b c Cite error: The named reference Soubiran2016 was invoked but never defined (see the help page).
  14. ^ a b c d Cite error: The named reference tokovinin2008 was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  16. ^ Cite error: The named reference wds was invoked but never defined (see the help page).
  17. ^ Cite error: The named reference baines was invoked but never defined (see the help page).