Phi Cygni

Short description: Star in the constellation Cygnus

φ Cygni

Location of φ Cygni (circled)

Observation data
Equinox J2000.0]] (ICRS)
Constellation | Cygnus
Right ascension |  19h 39m 22.60591s[1]
Declination | +30° 09′ 11.9604″[1]
Apparent magnitude (V) | 4.70[2] (5.31 + 5.6)[3]
Characteristics
Evolutionary stage | red clump[4][5]
Spectral type | G8III + G8III[6]
U−B color index | +0.81[2]
B−V color index | +0.98[2]
Astrometry
Radial velocity (Rv)| +4.50[7] km/s
Proper motion (μ)|  RA: +2.48[1] mas/yr
Dec.: +36.50[1] mas/yr
Parallax (π)| 14.9244 ± 0.4176[6] mas
Distance| 219 ± 6 ly
(67 ± 2 pc)
Absolute magnitude (MV)| +0.12[8] (+0.77/+1.07)[9]
Orbit
Period (P)| 434.208[10] days
Semi-major axis (a)| 26.9[3] mas″
Eccentricity (e)| 0.5557[10]
Inclination (i)| 80.8[3]°
Longitude of the node (Ω)| 251[3]°
Periastron epoch (T)| 2451239.58[10]
Argument of periastron (ω)
(secondary)| 209.41[10]°
Semi-amplitude (K1)
(primary)| 26.40[10] km/s
Semi-amplitude (K2)
(secondary)| 27.22[10] km/s
Details[6]

Mass| 2.104±0.049 M☉
Radius| 7.46[lower-alpha 1] R☉
Luminosity| 34.7+2.5
−2.3 L☉
Temperature| 5,130±120 K
Metallicity [Fe/H]| −0.11[10] dex
Rotational velocity (v sin i)| 4.7[10] km/s
Age| 479+58
−52 Myr

Mass| 2.040±0.042 M☉
Radius| 7.04[lower-alpha 2] R☉
Luminosity| 28±3 L☉
Temperature| 5,010 K
Rotational velocity (v sin i)| 4.8[10] km/s
Age| 562+69
−61 Myr
Other designations

φ Cygni, 12 Cygni, BD+29°3684, GC 27203, HD 185734, HIP 96683, HR 7478, SAO 68637, WDS J19394+3009AB[11]

Database references
SIMBAD| data

Phi Cygni, Latinized from φ Cygni, is a binary star[12] system in the northern constellation of Cygnus. It is faintly visible to the naked eye with an apparent visual magnitude of 4.70.[2] The annual parallax shift is 14.92 mas[6] as measured from Earth, which yields a distance estimate of around 220 light years. It is moving further from the Sun with a radial velocity of +4.5 km/s.[7]

φ Cygni is a double-lined spectroscopic binary system, which means that the absorption lines of both components are visible in the spectrum. The two sets of spectral lines are almost identical and both stars are assigned a spectral type of K0III, meaning they have evolved into giants. They are considered to be red clump giants, stars that have begun core helium fusion and lie on the horizontal branch but because of their metallicity and the size of their hydrogen envelope they are found very close to the red giant branch.[4][5] The two stars are assumed to have the same age, which would be around 650 million years.[13][9] The pair have an orbital period of 434.208 days, or 1.2 Earth years, a semimajor axis of 26.9 mas, and a high eccentricity of 0.56.[10]

## Notes

1. ↑ Calculated, using the Stefan-Boltzmann law and the star's effective temperature and luminosity, with respect to the solar nominal effective temperature of 5,772 K:(5,772103.71)4⋅101.53=7.46 R⊙.
2. ↑ Calculated, using the Stefan-Boltzmann law and the star's effective temperature and luminosity, with respect to the solar nominal effective temperature of 5,772 K:(5,772103.70)4⋅101.45=7.04 R⊙.

## References

1. ↑ 1.0 1.1 1.2 van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics 474 (2): 653–664. doi:10.1051/0004-6361:20078357. Bibcode: 2007A&A...474..653V. http://www.aanda.org/articles/aa/full/2007/41/aa8357-07/aa8357-07.html. Vizier catalog entry
2. ↑ 2.0 2.1 2.2 2.3 Fernie, J. D. (June 1969), "UBV observations of miscellaneous stars", Journal of the Royal Astronomical Society of Canada 63: 133–135, Bibcode: 1969JRASC..63..133F.
3. ↑ 3.0 3.1 3.2 3.3 Pourbaix, D (2000). "Resolved double-lined spectroscopic binaries: A neglected source of hypothesis-free parallaxes and stellar masses". Astronomy and Astrophysics Supplement 145 (2): 215–222. doi:10.1051/aas:2000237. Bibcode: 2000A&AS..145..215P.
4. ↑ 4.0 4.1 Fekel, F. C (2004). "The Spectroscopic Orbit of φ Cygni, a System with Two Late-Type Giants". The Environment and Evolution of Double and Multiple Stars 21: 63. Bibcode: 2004RMxAC..21...63F.
5. ↑ 5.0 5.1 Armstrong, J. T; Hummel, C. A; Quirrenbach, A; Buscher, D. F; Mozurkewich, D; Vivekanand, M; Simon, R. S; Denison, C. S et al. (1992). "The orbit of Phi Cygni measured with long-baseline optical interferometry - Component masses and absolute magnitudes". Astronomical Journal 104: 2217. doi:10.1086/116396. Bibcode: 1992AJ....104.2217A.
6. ↑ 6.0 6.1 6.2 6.3 Piccotti, Luca; Docobo, José Ángel; Carini, Roberta; Tamazian, Vakhtang S.; Brocato, Enzo; Andrade, Manuel; Campo, Pedro P. (2020-02-01), "A study of the physical properties of SB2s with both the visual and spectroscopic orbits", Monthly Notices of the Royal Astronomical Society 492 (2): 2709–2721, doi:10.1093/mnras/stz3616, ISSN 0035-8711, Bibcode: 2020MNRAS.492.2709P Phi Cygni's database entry at VizieR.
7. ↑ 7.0 7.1 Pourbaix, D. et al. (2004), "SB9: The Ninth Catalogue of Spectroscopic Binary Orbits", Astronomy & Astrophysics 424 (2): 727–732, doi:10.1051/0004-6361:20041213, Bibcode: 2004A&A...424..727P.
8. ↑ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A.
9. ↑ 9.0 9.1 Armstrong, J. T; Hummel, C. A; Quirrenbach, A; Buscher, D. F; Mozurkewich, D; Vivekanand, M; Simon, R. S; Denison, C. S et al. (1992). "The orbit of Phi Cygni measured with long-baseline optical interferometry - Component masses and absolute magnitudes". Astronomical Journal 104: 2217. doi:10.1086/116396. Bibcode: 1992AJ....104.2217A.
10. ↑ 10.00 10.01 10.02 10.03 10.04 10.05 10.06 10.07 10.08 10.09 Massarotti, Alessandro; Latham, David W; Stefanik, Robert P; Fogel, Jeffrey (2008). "Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity". The Astronomical Journal 135 (1): 209–231. doi:10.1088/0004-6256/135/1/209. Bibcode: 2008AJ....135..209M.
11. ↑ "* phi Cyg". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=*+phi+Cyg.
12. ↑ Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society 389 (2): 869–879, doi:10.1111/j.1365-2966.2008.13596.x, Bibcode: 2008MNRAS.389..869E Vizier catalog entry
13. ↑ Soubiran, C; Bienaymé, O; Mishenina, T. V; Kovtyukh, V. V (2008). "Vertical distribution of Galactic disk stars. IV. AMR and AVR from clump giants". Astronomy and Astrophysics 480 (1): 91–101. doi:10.1051/0004-6361:20078788. Bibcode: 2008A&A...480...91S.

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Constellation of Cygnus

* List of stars in Cygnus

Stars|

| Bayer|

* α (Deneb)
* β (Albireo)
* γ (Sadr)
* δ (Fawaris)
* ε (Aljanah)
* ζ
* η
* θ
* ι1
* ι2
* κ
* λ
* μ
* ν
* ξ
* π1 (Azelfafage)
* π2
* ρ
* σ
* τ
* υ
* φ
* χ
* ψ
* ω1
* ω2
* P
* Q

|

Flamsteed|

* 2
* 4
* 8
* 9
* 14
* 15
* 16 (c)
* 17
* 20 (d)
* 22
* 23
* 26 (e)
* 27 (b1)
* 28 (b2)
* 29 (b3)
* 30
* 31
* 32
* 33
* 35
* 39
* 41
* 47
* 52
* 55
* 56
* 57
* 59 (f1)
* 61
* 63 (f2)
* 68 (A)
* 71 (g)
* 72
* 74
* 75

Variable|

* R
* T
* W
* RW
* SS
* TT
* BC
* BI
* CH
* KY
* V404
* V476
* V1057
* V1143
* V1191
* V1489
* V1500
* V1668
* V1974
* V2513

HR|

* 7633
* 7912
* 8193

HD|

* 185269
* 185435
* 187123
* 188753
* 191806

Gliese|

* 777
* 806
* 1245

Kepler|

* 5
* 6
* 11
* 15
* 16
* 17
* 18
* 22
* 23
* 27
* 28
* 29
* 31
* 32
* 33
* 34
* 35
* 36
* 39
* 40
* 41
* 42
* 43
* 44
* 45
* 47
* 51
* 56
* 61
* 66
* 67
* 68
* 69
* 70
* 78
* 80
* 84
* 86
* 89
* 107
* 182
* 186
* 223
* 371
* 419
* 432
* 451
* 452
* 1229
* 1520
* 1625

Other|

* AFGL 2591
* BD+40° 4210
* BD+43 3654
* Cygnus OB2 #8A
* Cygnus OB2 #12
* Cygnus X-1
* Cygnus X-3
* G 208-44
* G 208-45
* HAT-P-7
* HAT-P-11
* HAT-P-17
* KELT-9
* KIC 8462852
* KIC 9832227
* KIC 11026764
* KOI-74
* KOI-81
* KOI-256
* KPD 1930+2752
* MWC 349
* N6946-BH1
* NML Cygni
* PH1
* PSR J2032+4127
* W75N(B)-VLA2
* WISE J2000+3629
* WR 134
* WR 135
* WR 136
* WR 137
* WR 140
* WR 142
* WR 147
* WR 148

Former|

* 3

Star
clusters|

| Association|

* Cygnus OB2
* Cygnus OB7

|

Open|

* DR 6
* IC 5146
* Messier 29
* Messier 39
* NGC 6811
* NGC 6819
* NGC 6834
* NGC 6866
* NGC 6871
* NGC 6910

Molecular
clouds|

* Cygnus X (including DR 21)

Nebulae|

| Dark|

* Barnard 146
* Barnard 147
* IC 5146
* L1014

|

H II|

* NGC 6914
* North America Nebula
* Pelican Nebula
* Sadr Region
* Sh2-101
* Sh2-106

Planetary|

* Abell 78
* Egg Nebula
* IRAS 19475+3119
* Kronberger 61
* M1-92
* NGC 6826
* NGC 6881
* NGC 6884
* NGC 7008
* NGC 7026
* NGC 7027
* NGC 7048
* Soap Bubble Nebula

WR|

* Crescent Nebula

SNR|

* Cygnus Loop (including Veil Nebula)

Galaxies|

| NGC|

* 6801
* 6946
* 7013

|

Other|

* 3C 438
* Cygnus A

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