View source for 47 Cygni

{{short description|Star in the constellation Cygnus}}
{{Use mdy dates|date=May 2024}}
{{Starbox begin
 | name     = 47 Cygni
}}
{{Starbox image
| image = [[Image:V2125CygLightCurve.png|250px]]
| caption = A [[light curve]] for V2125 Cygni, plotted from ''[[Hipparcos]]'' data<ref name="CDS"/>
}}
{{Starbox observe
 | epoch    = J2000
 | constell = [[Cygnus (constellation)|Cygnus]]
 | ra       = {{RA|20|33|54.18809}}<ref name=DR3/>
 | dec      = {{DEC|+35|15|03.0390}}<ref name=DR3/>
 | appmag_v = 4.61<ref name=Ginestet2002/> {{nowrap|(4.84 + 7.30)}}<ref name=Eggleton2008/>
}}
{{Starbox character
 | type     = 
 | class    = {{nowrap|K6: Ib + B2.5:}}<ref name=Ginestet2002/>
 | b-v      = {{Val|1.593|0.023}}<ref name=Anderson2012/>
 | u-b      = 
 | variable = [[Slow irregular variable|Lc]]<ref name=gcvs/>
}}
{{Starbox astrometry
 | radial_v = {{Val|−4.6|0.3}}<ref name=Gontcharov2006/>
 | prop_mo_ra  = −6.12
 | prop_mo_dec = −4.166
 | pm_footnote = <ref name=DR3/>
 | parallax = 0.8792
 | p_error  = 0.196
 | parallax_footnote = <ref name=DR3/>
 | dist_pc = {{val|1249|296|237}}
 | dist_ly = {{val|4072|965|773}}
 | dist_footnote = <ref name="bailer-jones"/>
 | absmag_v = −4.1 {{nowrap|(−4 + −1.5)}}<ref name=Ginestet2002/>
}}
{{Starbox orbit
 | reference = <ref name=Griffin1992/>
 | 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}}<ref name=Tetzlaff2011/><br />{{val|19.4|3.9}}<ref name=kervella/>
 | radius   = {{solar radius calculator|type=AD|4.472|1.249}}<ref name=lang2006/>
 | luminosity  = 
 | temperature = 4,217<ref name=Soubiran2016/>
 | gravity  = 1.23<ref name=Soubiran2016/>
 | metal_fe = 0.13<ref name=Soubiran2016/>
 | rotational_velocity = 
 | age_myr  = {{Val|17.6|0.6}}<ref name=Tetzlaff2011/>
}}
{{Starbox detail|no_heading=y
 | component1 = 47 Cyg Ab
 | mass     = 0.57<ref name=tokovinin2008/>
 | component2 = 47 Cyg B
 | mass2    = 10.96<ref name=tokovinin2008/>
}}
{{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}}<ref name=SIMBAD/>
}}
{{Starbox reference
 | Simbad=47+Cyg
}}
{{Starbox end}}

'''47 Cygni''' is a [[triple star]]<ref name=Eggleton2008/><ref name=wds/> system in the northern [[constellation]] of [[Cygnus (constellation)|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.<ref name=Ginestet2002/> The system is moving closer to the Earth with a heliocentric [[radial velocity]] of {{val|−4.6|u=km/s}}.<ref name=Gontcharov2006/>

The dual nature of this system was recognized by [[Annie Cannon]] in 1912, and she assigned the pair separate [[Henry Draper Catalogue]] identifiers.<ref name=Griffin1992/> They orbit each other with a period of around {{Convert|52481|days|years|disp=out}}.<ref name=tokovinin2008/> The primary component is itself a [[spectroscopic binary]] in a near circular orbit with a [[orbital period|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 imaging|speckle interferometery]] since 1973. Radio emission was detected from this system in 1985/86.<ref name=Griffin1992/>

The supergiant primary is a [[slow irregular variable]] with an amplitude of about 0.1 magnitudes.<ref name=gcvs/> Its [[angular diameter]] has been measured at {{val|4.472|0.017}}{{nbsp}}[[milliarcsecond]]s using [[interferometry]] by the [[Navy Precision Optical Interferometer]].<ref name="baines"/> At the distance of 1,249{{nbsp}}[[parsec]]s,<ref name="bailer-jones"/> it yield a radius of {{solar radius calculator|type=AD|4.472|1.249|unit=y|link=y}}.<ref name=lang2006/> Its close companion has 57% of the [[mass of the Sun]].<ref name=tokovinin2008/>  The secondary is a hot [[B-type main-sequence star]], but still 2.5 magnitudes fainter than the primary.<ref name=Eggleton2008/>

==References==
{{reflist|refs=

<ref name=SIMBAD>{{cite simbad | title=47 Cyg | access-date=2019-01-14 }}</ref>

<ref name=DR3>{{Cite DR3|2056616231822305280}}</ref>

<ref name="CDS">{{cite web
 | 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}}</ref>

<!-- <ref name=tess>{{cite journal
 | bibcode=2019AJ....158..138S
 | title=The revised TESS Input Catalog and Candidate Target List
 | author=Stassun K.G.| display-authors=etal | date=October 2019
 | journal=[[The Astronomical Journal]] | volume=158 | issue=4 | page=138
 | arxiv=1905.10694 | doi=10.3847/1538-3881/ab3467 | s2cid=166227927 | doi-access=free
 }}</ref> -->

<ref name=Anderson2012>{{cite journal
 | 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 }}</ref>

<ref name=Soubiran2016>{{cite journal
 | 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 }}</ref>

<ref name=lang2006>{{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<sub>*</sub>) is given by:
:<math>\begin{align} 2\cdot R_*
 & = \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}</math></ref>

<ref name=Tetzlaff2011>{{cite journal
 | 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 }}</ref>

<ref name=kervella>{{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]].</ref>

<ref name=Eggleton2008>{{cite journal
 | 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 }}</ref>

<ref name=Griffin1992>{{cite journal
 | 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 }}</ref>

<ref name=Ginestet2002>{{cite journal
 | 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 }}</ref>

<ref name=wds>{{cite journal
 | 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 }}</ref>

<ref name=tokovinin2008>{{cite journal
 | 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
 }}</ref>

<ref name=Gontcharov2006>{{cite journal
 | 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 }}</ref>

<ref name=gcvs>{{cite journal
 | 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 }}</ref>

<ref name="bailer-jones">{{Cite journal |last1=Bailer-Jones |first1=C. A. L. |last2=Rybizki |first2=J. |last3=Fouesneau |first3=M. |last4=Demleitner |first4=M. |last5=Andrae |first5=R. |date=2021-03-01 |title=Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3 |journal=The Astronomical Journal |volume=161 |issue=3 |pages=147 |doi=10.3847/1538-3881/abd806 |doi-access=free |arxiv=2012.05220 |bibcode=2021AJ....161..147B |issn=0004-6256}} [https://dc.zah.uni-heidelberg.de/gedr3dist/q/cone/form Gaia eDR3 source] for this star.</ref>

<ref name="baines">{{Cite journal |last1=Baines |first1=Ellyn K. |last2=Clark III |first2=James H. |last3=Schmitt |first3=Henrique R. |last4=Stone |first4=Jordan M. |last5=von Braun |first5=Kaspar |date=2023-12-01 |title=33 New Stellar Angular Diameters from the NPOI, and Nearly 180 NPOI Diameters as an Ensemble |journal=The Astronomical Journal |volume=166 |issue=6  |pages=268 |doi=10.3847/1538-3881/ad08be |doi-access=free |bibcode=2023AJ....166..268B |issn=0004-6256}}</ref>

}}

{{Stars of Cygnus}}

[[Category:K-type supergiants]]
[[Category:B-type main-sequence stars]]
[[Category:Triple stars]]
[[Category:Spectroscopic binaries]]
[[Category:Cygnus (constellation)]]
[[Category:2MASS objects|J20335419+3515031]]
[[Category:Durchmusterung objects|BD+34 4079]]
[[Category:Flamsteed objects|Cygni, 47]]
[[Category:Henry Draper Catalogue objects|196094]]
[[Category:Hipparcos objects|101474]]
[[Category:Bright Star Catalogue objects|7866]]
[[Category:Slow irregular variables]]
[[Category:Objects with variable star designations|Cygni, V2125]]