View source for 16 Cygni

{{short description|Multiple star in the constellation Cygnus}}
{{good article}}
{{Starbox begin}}
{{Starbox image
 | image=
{{Location mark
|image=Cygnus constellation map.svg|alt=|float=center|width=260
|label=|position=right
|mark=Red circle.svg|mark_width=10|mark_link=16 Cygni
|x=552|y=200
}}
|caption=Location of 16 Cygni (circled)
}}
{{Starbox observe 3s
| epoch = J2000.0
| constell = [[Cygnus (constellation)|Cygnus]]<ref name=constellation/>
| component1 = 16 Cygni A
| ra1 = {{RA|19|41|48.9535}}<ref name="Gaia DR3 A"/>
| dec1 = {{DEC|+50|31|30.220}}<ref name="Gaia DR3 A"/>
| appmag_v1 = 5.96
| component2 = 16 Cygni B
| ra2 = {{RA|19|41|51.9727}}<ref name="Gaia DR3 B"/>
| dec2 = {{DEC|+50|31|03.089}}<ref name="Gaia DR3 B"/>
| appmag_v2 = 6.20
| component3 = 16 Cygni C
| ra3 = {{RA|19|48|48.8007}}<ref name="Gaia DR3 C"/>
| dec3 = {{DEC|+50|31|27.019}}<ref name="Gaia DR3 C"/>
| appmag_v3 = 
}}
{{Starbox character
| class = G1.5Vb / G2.5Vb / M?V{{cn|date=June 2025}}
| r-i = <!--R-I color-->
| v-r = <!--V-R color-->
| b-v = 0.64 / 0.66 / ?{{cn|date=June 2025}}
| u-b = 0.19 / 0.20 / ?{{cn|date=June 2025}}
| variable = ''None''{{cn|date=June 2025}}
}}
{{Starbox astrometry
| component1 = 16 Cyg A
| radial_v = {{val|−27.31|(13)}}<ref name="Gaia DR3 A"/>
| prop_mo_ra = {{val|−148.034|(28)}}
| prop_mo_dec = {{val|−159.030|(28)}}
| pm_footnote = <ref name="Gaia DR3 A"/>
| parallax = 47.3239
| p_error = 0.0197
| parallax_footnote = <ref name="Gaia DR3 A"/>
| absmag_v = 4.32<ref name=grether2006/>
| component2 = 16 Cyg B
| radial_v2 = {{val|−27.87|(12)}}<ref name="Gaia DR3 B"/>
| prop_mo_ra2 = {{val|−134.482|(18)}}
| prop_mo_dec2 = {{val|−162.698|(27)}}
| pm_footnote2 = <ref name="Gaia DR3 B"/>
| parallax2 = 47.3302
| p_error2 = 0.0171
| parallax_footnote2 = <ref name="Gaia DR3 B"/>
| absmag_v2 = 4.60<ref name=holmberg2009/>
}}
{{Starbox astrometry|no_heading=y
| component1 = 16 Cyg C
| radial_v = 
| prop_mo_ra = {{val|−152.718|(205)}}
| prop_mo_dec = {{val|−137.818|(146)}}
| pm_footnote = <ref name="Gaia DR3 C"/>
| parallax = 47.3292
| p_error = 0.1225
| parallax_footnote = <ref name="Gaia DR3 C"/>
| absmag_v = 
}}
{{Starbox detail
| component1 = 16 Cyg A
| mass = {{val|1.057|0.008}}<ref name=Buldgen2025/>
| radius = {{val|1.216|0.005}}<ref name=Buldgen2025/>
| luminosity = {{val|1.55|0.07}}<ref name="Metcalfe2015"/>
| gravity = {{val|4.292|0.003}}<ref name="Metcalfe2015"/>
| temperature = {{val|fmt=commas|5,830|11}}<ref name=TucciMaia2014>{{cite journal| bibcode=2014ApJ...790L..25T| title=High Precision Abundances in the 16 Cyg Binary System: A Signature of the Rocky Core in the Giant Planet| journal=The Astrophysical Journal| volume=790| issue=2| pages=L25| last1=Tucci Maia| first1=Marcelo| last2=Meléndez| first2=Jorge| last3=Ramírez| first3=Iván| year=2014| doi=10.1088/2041-8205/790/2/L25| arxiv=1407.4132| s2cid=118403440}}</ref>
| metal_fe = {{val|0.101|0.008}}<ref name="TucciMaia2014" />
| rotation = 23.8{{±|1.5|1.8}} d<ref name=Davies2015/>
| rotational_velocity = {{val|2.23|0.07}}<ref name=Davies2015>{{cite journal|bibcode=2015MNRAS.446.2959D|title=Asteroseismic inference on rotation, gyrochronology and planetary system dynamics of 16 Cygni|journal=Monthly Notices of the Royal Astronomical Society|volume=446|issue=3|pages=2959|last1=Davies|first1=G. R|last2=Chaplin|first2=W. J|last3=Farr|first3=W. M|last4=García|first4=R. A|last5=Lund|first5=M. N|last6=Mathis|first6=S|last7=Metcalfe|first7=T. S|last8=Appourchaux|first8=T|last9=Basu|first9=S|last10=Benomar|first10=O|last11=Campante|first11=T. L|last12=Ceillier|first12=T|last13=Elsworth|first13=Y|last14=Handberg|first14=R|last15=Salabert|first15=D|last16=Stello|first16=D|year=2015|doi=10.1093/mnras/stu2331|doi-access=free |arxiv=1411.1359|s2cid=119110862}}</ref>
| age_gyr = {{val|7.01|0.10}}<ref name=Buldgen2025/>
| component2 = 16 Cyg B
| mass2 = {{val|1.010|0.024}}<ref name=Buldgen2025/>
| radius2 = {{val|1.105|0.009}}<ref name=Buldgen2025/>
| luminosity2 = {{val|1.25|0.05}}<ref name="Metcalfe2015"/>
| gravity2 = {{val|4.359|0.002}}<ref name="Metcalfe2015"/>
| temperature2 = {{val|fmt=commas|5,751|11}}<ref name=TucciMaia2014/>
| metal2_fe = {{val|0.054|0.008}}<ref name="TucciMaia2014" />
| rotation2 = 23.2{{±|11.5|3.2}} d<ref name=Davies2015/>
| rotational_velocity2 = {{val|1.35|0.08}}<ref name=Davies2015/>
| age_gyr2 = {{val|7.06|0.11}}<ref name=Buldgen2025/>
}}
{{Starbox catalog
| component = 16 Cygni AB
| names = [[Struve Double Star Catalog|Struve]] 4046, [[GJ catalog|GJ]] 765.1
| component2 = 16 Cygni A
| names2 = {{odlist |BD=+50 2847 |GCTP=4634.00 |HD=186408 |HIP=96895 |HR= 7503 |LTT=15750 |SAO=31898 |Gaia DR3=2135550755683405952 }}
| component3 = 16 Cygni B
| names3 = {{odlist |BD=+50 2848 |HD=186427 |HIP=96901 |HR=7504 |LTT=15751 |SAO=31899 |KIC=12069449 |Gaia DR3=2135550755683407232 }}
| component4 = 16 Cygni C
| names4 = {{odlist |Gaia DR3=2135550755684554112 }}
}}
{{Starbox reference
| Simbad = 16+Cygni
| Simbad2 = HD+186408 | sn2=A
| Simbad3 = HD+186427 | sn3=B
| Simbad4 = 16+Cyg+C | sn4=C
| EPE = 16+Cyg+B
| ARICNS = <!--Code-->
}}
{{Starbox end}}
'''16 Cygni''' or '''16 Cyg''' is a [[triple star]] system approximately 69 [[light-year]]s away from Earth in the [[constellation]] of [[Cygnus (constellation)|Cygnus]].  It consists of two [[Sun]]-like [[Yellow dwarf star|yellow dwarf]] stars, 16 Cygni A and 16 Cygni B, together with a [[red dwarf]], 16 Cygni C. In 1996 an [[extrasolar planet]] was discovered in an [[eccentricity (orbit)|eccentric]] [[orbit]] around 16 Cygni B.

==Distance==
The parallax of the two brightest stars were measured as part of the [[Hipparcos]] [[astrometry]] mission. This yielded a parallax of 47.44 [[milliarcsecond]]s for 16 Cygni A<ref name="van Leeuwen2007"/> and 47.14 milliarcseconds for 16 Cygni B.<ref name="van Leeuwen2007"/> Since the two components are associated, it is reasonable to assume they lie at the same distance, so the different parallaxes are a result of experimental error (indeed, when the associated parallax errors are taken into account, the ranges of the parallaxes overlap). Using the parallax of the A component, the distance is 21.1 [[parsec]]s. The parallax of the B component corresponds to a distance of 21.2 [[parsec]]s.

==Stellar components==
[[File:16 Cygni.jpg|thumb|left|16 Cygni in optical light]]
16 Cygni is a hierarchical triple system. Stars A and C form a close binary with a [[projected separation]] of 73 [[Astronomical unit|AU]].<ref name="raghavan">{{cite journal | author=Raghavan | title=Two Suns in The Sky: Stellar Multiplicity in Exoplanet Systems | journal=The Astrophysical Journal | volume=646 | issue=1 | pages=523–542 | date=2006 | doi=10.1086/504823 | last2=Henry | first2=Todd J. | last3=Mason | first3=Brian D. | last4=Subasavage | first4=John P. | last5=Jao | first5=Wei-Chun | last6=Beaulieu | first6=Thom D. | last7=Hambly | first7=Nigel C. | bibcode=2006ApJ...646..523R | arxiv=astro-ph/0603836 | s2cid=5669768 | display-authors=etal }}</ref> The [[orbital elements]] of the A–C binary are currently unknown. At a distance of 860 AU from A is a third component designated 16 Cygni B. The [[orbit]] of B relative to the A–C pair was determined in 1999 and not updated since (as of June 2007): plausible orbits range in period from 18,200 to 1.3 million years, with a [[semimajor axis]] ranging from 877 to 15,180 AU. In addition B orbits between 100 and 160 degrees inclination, that is against the A–C pole such that 90 degrees would be ecliptical.<ref>{{cite journal | author=Hauser, H. | author2=Marcy, G. | title=The Orbit of 16 Cygni AB | journal=[[Publications of the Astronomical Society of the Pacific]] | volume=111 | issue=757 | pages=321–334 | date=1999 | doi=10.1086/316328 | bibcode=1999PASP..111..321H| doi-access=free }}</ref>

Both 16 Cygni A and 16 Cygni B are [[Yellow dwarf star|yellow dwarf]] stars similar to the [[Sun]]. Their [[spectral type]]s have been given as G1.5V and G3V,<ref>{{citation|bibcode=2003AJ....126.2048G|title=Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 Parsecs: The Northern Sample. I|journal=The Astronomical Journal|volume=126|issue=4|pages=2048|last1=Gray|first1=R. O|last2=Corbally|first2=C. J|last3=Garrison|first3=R. F|last4=McFadden|first4=M. T|last5=Robinson|first5=P. E|year=2003|doi=10.1086/378365|arxiv=astro-ph/0308182|s2cid=119417105}}</ref> with A being a little hotter than the Sun, and B somewhat cooler. The system was within the field of view of the original mission of the ''[[Kepler (spacecraft)|Kepler]]'' spacecraft, which collected extremely precise [[photometry (astronomy)|photometric]] data of the stars. From these measurements, [[asteroseismology]] models have calculated precise masses of 1.08 and 1.04 times the [[solar mass]] for 16 Cygni A and 16 Cygni B respectively, and independent ages of around 7 billion years for each star.<ref name=Metcalfe2015/> In a 2018 PhD dissertation, astrophysicist Earl Patrick Bellinger used asteroseismic inversion techniques to perform a detailed model-independent analysis of the internal structures of 16 Cyg A and B. While 16 Cyg B’s internal profile closely matched theoretical stellar evolution models, 16 Cyg A showed significant deviations in its core structure compared to best-fitting models. This suggests that standard stellar models may not fully capture the internal physics of stars slightly more massive than the Sun, and highlights the value of asteroseismic inversion for refining stellar theory.{{cn|date=June 2025}} The system has also been observed through [[interferometry]], which allowed the determination of the [[angular diameter]] of each star.<ref name=White2013>{{cite journal|bibcode=2013MNRAS.433.1262W|title=Interferometric radii of bright Kepler stars with the CHARA Array: θ Cygni and 16 Cygni a and B|journal=Monthly Notices of the Royal Astronomical Society|volume=433|issue=2|pages=1262|last1=White|first1=T. R|last2=Huber|first2=D|last3=Maestro|first3=V|last4=Bedding|first4=T. R|last5=Ireland|first5=M. J|last6=Baron|first6=F|last7=Boyajian|first7=T. S|last8=Che|first8=X|last9=Monnier|first9=J. D|last10=Pope|first10=B. J. S|last11=Roettenbacher|first11=R. M|last12=Stello|first12=D|last13=Tuthill|first13=P. G|last14=Farrington|first14=C. D|last15=Goldfinger|first15=P. J|last16=McAlister|first16=H. A|last17=Schaefer|first17=G. H|last18=Sturmann|first18=J|last19=Sturmann|first19=L|last20=Ten Brummelaar|first20=T. A|last21=Turner|first21=N. H|year=2013|doi=10.1093/mnras/stt802|doi-access=free |arxiv=1305.1934|s2cid=8165381}}</ref> The angular diameters together with the asteroseismology models were used to calculate radii of 1.229 and 1.116 times the [[solar radius]] for components A and B respectively.<ref name=Metcalfe2015/>

===Abundances===
Despite having the same age and presumably the same primordial composition, observations show a small difference in the [[metallicity]] of the two 16 Cygni stars. The primary star has an iron abundance of 1.26 times the solar value, compared to 1.13 for the secondary star. A similar trend has been found for all other metals, with the primary component having an average of 10% more metals than B. One possibility is that this difference is linked to the planet 16 Cygni Bb, since its formation may have removed metals from the [[protoplanetary disk]] around 16 Cygni B.<ref name=Ramírez2011>{{cite journal|bibcode=2011ApJ...740...76R|title=Elemental Abundance Differences in the 16 Cygni Binary System: A Signature of Gas Giant Planet Formation?|journal=The Astrophysical Journal|volume=740|issue=2|pages=76|last1=Ramírez|first1=I|last2=Meléndez|first2=J|last3=Cornejo|first3=D|last4=Roederer|first4=I. U|last5=Fish|first5=J. R|year=2011|doi=10.1088/0004-637X/740/2/76|arxiv=1107.5814|s2cid=119257511}}</ref><ref name=TucciMaia2014/> However, another study found no difference in heavy element abundances between 16 Cygni A and B.<ref name=Schuler2011>{{cite journal|bibcode=2011ApJ...737L..32S|title=Detailed Abundances of the Solar Twins 16 Cygni a and B: Constraining Planet Formation Models|journal=The Astrophysical Journal|volume=737|issue=2|pages=L32|last1=Schuler|first1=Simon C|last2=Cunha|first2=Katia|last3=Smith|first3=Verne V|last4=Ghezzi|first4=Luan|last5=King|first5=Jeremy R|last6=Deliyannis|first6=Constantine P|last7=Boesgaard|first7=Ann Merchant|year=2011|doi=10.1088/2041-8205/737/2/L32|arxiv=1107.3183|doi-access=free}}</ref>

Another chemical peculiarity between the stars is in their [[lithium]] abundance. Measurements of the lithium abundance in the system show a 4 times higher abundance in component A than in 16 Cygni B. Compared to the Sun, 16 Cygni A has 1.66 as much lithium, while 16 Cygni B has only 0.35.<ref name=Deal2015>{{cite journal |last1=Deal |first1=Morgan |last2=Richard |first2=Olivier |last3=Vauclair |first3=Sylvie |author-link3=Sylvie Vauclair |title=Accretion of planetary matter and the lithium problem in the 16 Cygni stellar system |journal=Astronomy & Astrophysics |date=1 December 2015 |volume=584 |pages=A105 |doi=10.1051/0004-6361/201526917|bibcode=2015A&A...584A.105D|arxiv=1509.06958|s2cid=119293969 }}</ref> It has been hypothesized that the [[accretion (astrophysics)|accretion]] of about 1 [[Earth mass]] of metals by 16 Cygni B soon after the system's formation may have destroyed the lithium in the star's atmosphere.<ref name=Deal2015/> Another proposed scenario is the engulfment of a Jupiter-mass planet by 16 Cygni A, which increased the amount of lithium in the star's outer atmosphere.<ref>{{citation
 | title=Correlation between lithium abundances and ages of solar twin stars
 | display-authors=1 | last1=Carlos | first1=Marília
 | last2=Nissen | first2=Poul E. | last3=Meléndez | first3=Jorge
 | journal=Astronomy & Astrophysics
 | volume=587 | issue=100 | id=A100 | pages=6 | date=March 2016
 | doi=10.1051/0004-6361/201527478 | bibcode=2016A&A...587A.100C
 | arxiv=1601.05054 | s2cid=119268561 | postscript=. <!-- | class=astro-ph.SR --> }}</ref>

==Planetary system==
In 1996 an [[extrasolar planet]] in an [[eccentricity (orbit)|eccentric]] orbit was announced around the star 16 Cygni B.<ref name="WaPo"/> The discovery by the [[radial velocity method]] was made from independent observations from the [[McDonald Observatory]] and [[Lick Observatory]].<ref>{{citation|bibcode=1996DPS....28.1204C|title=Detection of a planetary companion to 16 Cygni B|journal=AAA/Division for Planetary Sciences Meeting Abstracts|issue=28| pages=12.04|last1=Cochran|first1=W. D|last2=Hatzes|first2=A. P|last3=Butler|first3=R. P|last4=Marcy|first4=G. W|year=1996|volume=28}}</ref><ref name="Cochran1997"/> The planet's orbit takes 799.5 days to complete, with a semimajor axis of 1.69 AU.<ref name="Plávalová2013"/> It has a very high eccentricity of 0.69, which might be the result of gravitational perturbations from 16 Cygni A. In particular, simulations show the planet's eccentricity oscillates between low and high values in timescales of tens of millions of years.<ref>{{cite journal|bibcode=1997Natur.386..254H|title=Chaotic variations in the eccentricity of the planet orbiting 16 Cygni B|journal=Nature|volume=386|issue=6622|pages=254|last1=Holman|first1=Matthew|last2=Touma|first2=Jihad|last3=Tremaine|first3=Scott|year=1997|doi=10.1038/386254a0|s2cid=4312547}}</ref><ref>{{cite journal|bibcode=1997ApJ...477L.103M|title=The High Eccentricity of the Planet Orbiting 16 Cygni B|journal=The Astrophysical Journal|volume=477|issue=2|pages=L103|last1=Mazeh|first1=Tsevi|last2=Krymolowski|first2=Yuval|last3=Rosenfeld|first3=Gady|year=1997|doi=10.1086/310536|arxiv=astro-ph/9611135|s2cid=15736587}}</ref>

Like the majority of extrasolar planets detectable from Earth, [[16 Cygni Bb]] was deduced from the [[radial velocity]] of its parent star. At the time that only gave a lower limit on the mass: in this case, about 1.68 times that of [[Jupiter]]. In 2012, two astronomers, E. Plavalova and N.A. Solovaya, showed that the stable orbit would demand about 2.38 [[Jupiter mass]]es, such that its orbit was inclined at either 45° or 135°.<ref name="Plávalová2013"/>

The eccentric orbit and mass of 16 Cygni Bb makes it extremely unlikely that a terrestrial sized planet will be found orbiting within the star's habitable zone.<ref name="Wittenmyer2007"/> In a computer simulation, only particles inside approximately 0.3 AU remained stable within a million years of formation, leaving open the possibility of short-period planets. For them, observation rules out any such planet of over a Neptune mass.<ref name="Wittenmyer2007"/>

There was a [[Message to Extra-Terrestrial Intelligence|METI]] message sent to the 16 Cygni system. It was transmitted from [[Eurasia]]'s largest [[radar]]—the 70-meter (230-foot) [[Yevpatoria RT-70 radio telescope|Eupatoria Planetary Radar]]. The message was named [[Cosmic Call 1]]; it was sent on May 24, 1999, and it will reach 16 Cygni in November 2069.<ref>{{in lang|ru}} http://www.cplire.ru/rus/ra&sr/VAK-2004.html {{Webarchive|url=https://web.archive.org/web/20190530145209/https://www.plover.com/misc/Dumas-Dutil/messages.pdf |date=2019-05-30 }}</ref>

{{OrbitboxPlanet begin
| name=16 Cygni B
| table_ref = <ref name="Plávalová2013"/>
}}
{{OrbitboxPlanet
| exoplanet = [[16 Cygni Bb|b]]
| mass = {{val|2.38|0.04}}
| period = 799.5
| semimajor = 1.693
| eccentricity = {{val|0.689|0.011}}
}}
{{Orbitbox end}}

==See also==
* [[61 Cygni]]
* [[30 Arietis]]
* [[83 Leonis]]
* [[54 Piscium]]
* [[HD 20782]]
* [[HD 80606]]
* [[HD 89744]]
* [[HD 222582]]

==References==
{{reflist|refs=

<ref name="Gaia DR3 A">{{cite DR3|2135550755683405952}}</ref>

<ref name="Gaia DR3 B">{{cite DR3|2135550755683407232}}</ref>

<ref name="Gaia DR3 C">{{cite DR3|2135550755684554112}}</ref>

<ref name=constellation>{{cite constellation|16 Cygni}}</ref>

<ref name=holmberg2009>{{cite journal |last1=Holmberg |first1=J. |last2=Nordström |first2=B. |last3=Andersen |first3=J. |title=The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics |journal=Astronomy and Astrophysics |date=2009 |volume=501 |issue=3 |page=941 |doi=10.1051/0004-6361/200811191 |arxiv=0811.3982 |bibcode=2009A&A...501..941H }}</ref>

<ref name=grether2006>{{cite journal |last1=Grether |first1=Daniel |last2=Lineweaver |first2=Charles H. |title=How Dry is the Brown Dwarf Desert? Quantifying the Relative Number of Planets, Brown Dwarfs, and Stellar Companions around Nearby Sun-like Stars |journal=The Astrophysical Journal |date=2006 |volume=640 |issue=2 |page=1051 |doi=10.1086/500161 |arxiv=astro-ph/0412356 |bibcode=2006ApJ...640.1051G }}</ref>

<ref name="Cochran1997">{{cite journal | title=The Discovery of a Planetary Companion to 16 Cygni B | last1=Cochran | first1=William D. | last2=Hatzes | first2=Artie P. | last3=Butler | first3=R. Paul | last4=Marcy | first4=Geoffrey W. | display-authors=1 | journal=The Astrophysical Journal | volume=483 | issue=1 | pages=457–463 | year=1997 | arxiv=astro-ph/9611230 | bibcode=1997ApJ...483..457C | bibcode-access=free | doi=10.1086/304245 | doi-access=free }}</ref>

<ref name="Metcalfe2015">{{cite journal | title=Asteroseismic Modeling of 16 Cyg A & B using the Complete Kepler Data Set | last1=Metcalfe | first1=Travis S. | last2=Creevey | first2=Orlagh L. | last3=Davies | first3=Guy R. | journal=The Astrophysical Journal Letters | volume=811 | issue=2 | at=L37 | year=2015 | arxiv=1508.00946 | bibcode=2015ApJ...811L..37M | bibcode-access=free | doi=10.1088/2041-8205/811/2/L37 | doi-access=free }}</ref>

<ref name="Plávalová2013">{{cite journal | title=Analysis of the motion of an extrasolar planet in a binary system | last1=Plávalová | first1=Eva |last2=Solovaya | first2=Nina A. | journal=The Astronomical Journal | volume=146 | issue=5 | pages=108 | year=2013 | arxiv=1212.3843 | bibcode=2013AJ....146..108P | bibcode-access=free | doi=10.1088/0004-6256/146/5/108 | doi-access=free }}</ref>

<ref name="van Leeuwen2007">{{cite journal | title=Validation of the new Hipparcos reduction | last1=van Leeuwen | first1=F. | journal=Astronomy and Astrophysics | volume=474 | issue=2 | pages=653–664 | year=2007 | arxiv=0708.1752 | bibcode=2007A&A...474..653V | bibcode-access=free | doi=10.1051/0004-6361:20078357 | doi-access=free }} [http://webviz.u-strasbg.fr/viz-bin/VizieR-5?-out.add=.&-source=I/311/hip2&recno=96568 Vizier catalog entry for A ] [http://webviz.u-strasbg.fr/viz-bin/VizieR-5?-out.add=.&-source=I/311/hip2&recno=96574 Vizier catalog entry for B ]</ref>

<ref name="WaPo">{{cite news | title=Astronomers Discover a Large World of Extremes Orbiting a 'Solar Twin' | last=Sawyer | first=Kathy | date=October 23, 1996 | url=https://www.washingtonpost.com/archive/politics/1996/10/24/astronomers-discover-a-large-world-of-extremes-orbiting-a-solar-twin | newspaper=Washington Post | access-date=2024-12-18 | url-access=registration }}</ref>

<ref name="Wittenmyer2007">{{cite journal | title=Dynamical and Observational Constraints on Additional Planets in Highly Eccentric Planetary Systems | last1=Wittenmyer | first1=R. A. | last2=Endl | first2=M. | last3=Cochran | first3=W. D. | last4=Levison | first4=H. F. | display-authors=1 | journal=The Astronomical Journal | volume=134 | issue=3 | pages=1276–1284 | year=2007 | arxiv=0706.1962 | bibcode=2007AJ....134.1276W | bibcode-access=free | doi=10.1086/520880 | doi-access=free }}</ref>

<ref name=Buldgen2025>{{cite journal |last1=Buldgen |first1=G. |last2=Bétrisey |first2=J. |last3=Pezzotti |first3=C. |last4=Borisov |first4=S. |last5=Noels |first5=A. |title=Asteroseismic modelling of Kepler Legacy stars including lithium depletion |date=2025-08-25 |arxiv=2508.18016 |journal=[[Astronomy and Astrophysics]] |doi=10.1051/0004-6361/202556216 }}</ref>

}}

==External links==
* {{cite encyclopedia |url=http://exoplanet.eu/star.php?st=16+Cyg+B |archive-url=https://web.archive.org/web/20070314050403/http://exoplanet.eu/star.php?st=16+Cyg+B |url-status=dead |archive-date=March 14, 2007 |title=Notes for star 16 Cyg B |author=Jean Schneider |date=2011 |encyclopedia=[[Extrasolar Planets Encyclopaedia]] |access-date=30 September 2011}}
* {{cite web |url=http://stars.astro.illinois.edu/sow/16cyg.html |title=16 Cyg |access-date=2024-07-17 |website=Stars}}
* {{cite web |url=http://www.solstation.com/stars2/16cygni2.htm |title=16 Cygni 2? |access-date=2008-06-24 |website=SolStation}}
* {{cite web |url=http://www.astro.uiuc.edu/~kaler/sow/16cyg.html |title=16 Cygni-B |access-date=2008-06-24 |website=[[University of Illinois at Urbana-Champaign]] |publisher=The Planet Project |url-status=dead |archive-url=https://web.archive.org/web/20080518004546/http://www.astro.uiuc.edu/~kaler/sow/16cyg.html |archive-date=2008-05-18 }}
* {{cite web
 |url         = http://media4.obspm.fr/exoplanets/base/etoile.php?nom=16+Cyg+B
 |title       = 16 Cyg B
 |website     = Exoplanets
 |access-date  = 2009-05-03
 |archive-url  = https://web.archive.org/web/20091125002817/http://media4.obspm.fr/exoplanets/base/etoile.php?nom=16+Cyg+B
 |archive-date = 2009-11-25
 |url-status     = dead
}}
* {{WikiSky}}
{{Sky|19|41|51.9720|+|50|31|03.083|70.5}}

{{Stars of Cygnus}}
<!-- Properties -->
[[Category:G-type main-sequence stars]]
[[Category:Maunder Minimum]]
[[Category:Multi-star planetary systems|3]]
[[Category:Planetary systems with one confirmed planet]]
[[Category:Triple star systems]]
<!-- Other -->
[[Category:Cygnus (constellation)]]
[[Category:Durchmusterung objects|BD+50 2847 and BD+50 2848]]
[[Category:Flamsteed objects|Cygni, 16]]
[[Category:Gliese and GJ objects|0765.1]]
[[Category:Henry Draper Catalogue objects|186408 and 186427]]
[[Category:Hipparcos objects|096895 and 096901]]
[[Category:Bright Star Catalogue objects|7503 and 7504]]
[[Category:TIC objects]]