Delta Cygni

δ Cygni
Location of δ Cygni (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Cygnus
Right ascension 19h 44m 58.47854s[1]
Declination +45° 07′ 50.9161″[1]
Apparent magnitude (V) 2.87[2]
Characteristics
Spectral type A0 IV[3] (B9 III + F1 V[4])
U−B color index –0.10[5]
B−V color index –0.02[5]
Variable type Suspected[6]
Astrometry
Radial velocity (Rv)–20.1[7] km/s
Proper motion (μ) RA: +44.07[1] mas/yr
Dec.: +48.66[1] mas/yr
Parallax (π)19.77 ± 0.48 mas[1]
Distance165 ± 4 ly
(51 ± 1 pc)
Absolute magnitude (MV)−0.74[8]
Orbit[9]
PrimaryA
CompanionB
Period (P)780.27 yr
Semi-major axis (a)3.0″
Eccentricity (e)0.4670
Details[10]
Mass2.93 M☉
Radius4.81±0.36[11] R☉
Luminosity155 L☉
Surface gravity (log g)3.4±0.25[11] cgs
Temperature10400±400[11] K
Rotational velocity (v sin i)142[11] km/s
Other designations
Fawaris, δ Cyg, 18 Cygni, 18 Cyg, BD+44°3234, HD 186882, HIP 97165, HR 7528, SAO 48796, WDS J19450+4508AB
Database references
SIMBADdata

Delta Cygni (δ Cygni, abbreviated Delta Cyg, δ Cyg) is a binary star of a combined third-magnitude in the constellation of Cygnus. It is also part of the Northern Cross asterism whose brightest star is Deneb. Based upon parallax measurements obtained during the Hipparcos mission, Delta Cygni is located roughly 165 light-years (51 parsecs) distant from the Sun.[1]

Delta Cygni's two components are designated Delta Cygni A (officially named Fawaris /fəˈwɛərɪs/)[12] and B. More widely separated is a faint third component, a 12th magnitude star that is moving along with the others. Together they form a triple star system.[13]

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  10. ^ Cite error: The named reference challouf2014 was invoked but never defined (see the help page).
  11. ^ a b c d Cite error: The named reference gordon2019 was invoked but never defined (see the help page).
  12. ^ "Naming Stars". IAU.org. Retrieved 18 June 2018.
  13. ^ Cite error: The named reference kalerAC was invoked but never defined (see the help page).