47 Cygni
{{short description|Star in the constellation Cygnus}}
{{Use mdy dates|date=May 2024}}
{{Starbox begin
| name = 47 Cygni
}}
{{Starbox image
| image = 250px
| caption = A light curve for V2125 Cygni, plotted from Hipparcos data
}}
{{Starbox observe
| epoch = J2000
| constell = Cygnus
| dec = {{DEC|+35|15|03.0390}}
| appmag_v = 4.61 {{nowrap|(4.84 + 7.30)}}
}}
{{Starbox character
| type =
| class = {{nowrap|K6: Ib + B2.5:}}
| u-b =
| variable = Lc
}}
{{Starbox astrometry
| prop_mo_ra = −6.12
| prop_mo_dec = −4.166
| parallax = 0.8792
| p_error = 0.196
| dist_pc = {{val|1249|296|237}}
| dist_ly = {{val|4072|965|773}}
| absmag_v = −4.1 {{nowrap|(−4 + −1.5)}}
}}
{{Starbox orbit
| period_unitless = {{Val|1117|11|u=days}}
| eccentricity = 0.00 (assumed)
| periastron = {{Val|2447088|10|ul=JD|fmt=commas}}
| k1 = {{Val|2.0|0.1}}
}}
{{Starbox detail
| source =
| component1 = 47 Cyg Aa
| mass = {{Val|12.1|0.2}}
{{val|19.4|3.9}}
| radius = {{solar radius calculator|type=AD|4.472|1.249}}
| luminosity =
| rotational_velocity =
}}
{{Starbox detail|no_heading=y
| component1 = 47 Cyg Ab
| component2 = 47 Cyg B
}}
{{Starbox catalog
| names = {{odlist | V=V2125 Cyg | F=47 Cyg | BD=+34°4079 | HD=196093/196094 | HIP=101474 | HR=7866 | SAO=70203 | GC=28630 | WDS=J20339+3515|2MASS=J20335419+3515031}}
}}
{{Starbox reference
| Simbad=47+Cyg
}}
{{Starbox end}}
47 Cygni is a triple star system in the northern constellation of Cygnus, and is located around {{val|fmt=commas|4,000|ul=light years}} from the Earth. It is visible to the naked eye with a combined apparent visual magnitude of 4.61. The system is moving closer to the Earth with a heliocentric radial velocity of {{val|−4.6|u=km/s}}.
The dual nature of this system was recognized by Annie Cannon in 1912, and she assigned the pair separate Henry Draper Catalogue identifiers. They orbit each other with a period of around {{Convert|52481|days|years|disp=out}}. The primary component is itself a spectroscopic binary in a near circular orbit with a period of around {{Convert|1117|days|years|disp=out}}. The a sin i value for the primary is {{Convert|30.8|±|1.6|Gm|AU|abbr=on|lk=out}}, 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.
The supergiant primary is a slow irregular variable with an amplitude of about 0.1 magnitudes. Its angular diameter has been measured at {{val|4.472|0.017}}{{nbsp}}milliarcseconds using interferometry by the Navy Precision Optical Interferometer. At the distance of 1,249{{nbsp}}parsecs, it yield a radius of {{solar radius calculator|type=AD|4.472|1.249|unit=y|link=y}}. Its close companion has 57% of the mass of the Sun. The secondary is a hot B-type main-sequence star, but still 2.5 magnitudes fainter than the primary.
References
{{reflist|refs=
{{cite simbad | title=47 Cyg | access-date=2019-01-14 }}
{{Cite DR3|2056616231822305280}}
| url=https://cdsarc.cds.unistra.fr/viz-bin/ftp-index?/ftp/cats/more/HIP/cdroms/cats
| website=Centre de Données astronomiques de Strasbourg | title=/ftp/cats/more/HIP/cdroms/cats
| publisher=Strasbourg astronomical Data Center |access-date=15 October 2022}}
| title=XHIP: An extended hipparcos compilation
| last1=Anderson | first1=E. | last2=Francis | first2=Ch.
| journal=Astronomy Letters
| volume=38 | issue=5 | pages=331 | year=2012
| bibcode=2012AstL...38..331A | doi=10.1134/S1063773712050015
| arxiv=1108.4971 | s2cid=119257644 }}
| title=The PASTEL catalogue: 2016 version
| last1=Soubiran | first1=Caroline | last2=Le Campion | first2=Jean-François
| last3=Brouillet | first3=Nathalie | last4=Chemin | first4=Laurent
| display-authors=1 | journal=Astronomy and Astrophysics
| volume=591 | pages=A118 | year=2016
| bibcode=2016A&A...591A.118S | doi=10.1051/0004-6361/201628497 | arxiv=1605.07384 | s2cid=119258214 }}
{{citation | first1=Kenneth R. | last1=Lang | title=Astrophysical formulae | volume=1 | series=Astronomy and astrophysics library | edition=3 | publisher=Birkhäuser | year=2006 | isbn=3-540-29692-1 | url=https://books.google.com/books?id=OvTjLcQ4MCQC&pg=PA41 }}. The radius (R*) is given by:
:
& = \frac{(10^{-3}\cdot 1,249\cdot 4.472)\ \text{AU}}{0.0046491\ \text{AU}/R_{\bigodot}} \\
& 1,201.4\cdot R_{\bigodot}
\end{align}
| last1=Tetzlaff | first1=N. | last2=Neuhäuser | first2=R. | last3=Hohle | first3=M. M.
| title=A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun
| journal=Monthly Notices of the Royal Astronomical Society
| volume=410 | issue=1 | pages=190–200 | date=January 2011
| doi=10.1111/j.1365-2966.2010.17434.x
| doi-access=free | bibcode=2011MNRAS.410..190T | arxiv=1007.4883 | s2cid=118629873 }}
{{Cite journal |last1=Kervella |first1=Pierre |last2=Arenou |first2=Frédéric |last3=Thévenin |first3=Frédéric |date=2022-01-01 |title=Stellar and substellar companions from Gaia EDR3. Proper-motion anomaly and resolved common proper-motion pairs |bibcode=2022A&A...657A...7K |journal=Astronomy and Astrophysics |volume=657 |pages=A7 |doi=10.1051/0004-6361/202142146 |issn=0004-6361|arxiv=2109.10912 }} [https://vizier.cds.unistra.fr/viz-bin/VizieR?-source=J/A%2BA/657/A7&HIP=101474 47 Cygni's database entry] at VizieR.
| last1=Eggleton | first1=P. P. | last2=Tokovinin | first2=A. A.
| title=A catalogue of multiplicity among bright stellar systems
| journal=Monthly Notices of the Royal Astronomical Society
| volume=389 | issue=2 | pages=869–879 | date=September 2008
| doi=10.1111/j.1365-2966.2008.13596.x | doi-access=free | bibcode=2008MNRAS.389..869E
| arxiv=0806.2878 | s2cid=14878976 }}
| title=Spectroscopic binary orbits from photoelectric radial velocities. Paper 104: 47 Cygni
| last1=Griffin | first1=R. F.
| journal=The Observatory
| volume=112 | pages=111–120 | date=June 1992
| bibcode=1992Obs...112..111G }}
| last1=Ginestet | first1=N. | last2=Carquillat | first2=J. M.
| title=Spectral Classification of the Hot Components of a Large Sample of Stars with Composite Spectra, and Implication for the Absolute Magnitudes of the Cool Supergiant Components
| journal=The Astrophysical Journal Supplement Series
| volume=143 | issue=2 | pages=513–537 | date=December 2002
| doi=10.1086/342942 | bibcode=2002ApJS..143..513G | doi-access=free }}
| title=The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog
| display-authors=1 | last1=Mason | first1=Brian D.
| last2=Wycoff | first2=Gary L. | last3=Hartkopf | first3=William I.
| last4=Douglass | first4=Geoffrey G. | last5=Worley | first5=Charles E.
| journal=The Astronomical Journal
| year=2001 | volume=122 | issue=6 | pages=3466
| bibcode=2001AJ....122.3466M | doi=10.1086/323920 | doi-access=free }}
| last1=Tokovinin | first1=A.
| title=Comparative statistics and origin of triple and quadruple stars
| journal=Monthly Notices of the Royal Astronomical Society
| volume=389 | issue=2 | pages=925–938 | year=2008
| doi=10.1111/j.1365-2966.2008.13613.x
| doi-access=free
| bibcode=2008MNRAS.389..925T | arxiv=0806.3263 | s2cid=16452670
}}
| title=Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system
| last1=Gontcharov | first1=G. A.
| date=2006 | journal=Astronomy Letters
| volume=32 | issue=11 | pages=759–771
| bibcode=2006AstL...32..759G | arxiv=1606.08053
| doi=10.1134/S1063773706110065 | s2cid=119231169 }}
| last1=Samus |first1=N. N. | last2=Durlevich |first2=O. V.
| display-authors=etal | volume=1 | year=2009
| title=VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)
| journal=VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S
| bibcode=2009yCat....102025S }}
}}
{{Stars of Cygnus}}
Category:B-type main-sequence stars
Category:Spectroscopic binaries
Category:Cygnus (constellation)