Editing Cygnus (constellation) (section)

=== Exoplanets ===
Cygnus is one of the constellations that the [[Kepler space telescope|Kepler satellite]] surveyed in its search for [[exoplanet]]s, and as a result, there are about a hundred stars in Cygnus with known planets, the most of any constellation.<ref name="KeplerLocation">{{cite web |url=http://www.nasa.gov/pdf/314125main_Kepler_presskit_2-19_smfile.pdf |archive-url=https://web.archive.org/web/20090304120931/http://www.nasa.gov/pdf/314125main_Kepler_presskit_2-19_smfile.pdf |archive-date=2009-03-04 |url-status=live |title=Kepler: NASA's First Mission Capable of Finding Earth-Size Planets |publisher=[[NASA]] |date=February 2009 |access-date=14 March 2009}}</ref> One of the most notable systems is the [[Kepler-11]] system, containing six [[transiting planet]]s, all within a plane of approximately one degree. It was the system with six exoplanets to be discovered.<ref name="Lissauer2011_Kepler-11">{{cite journal | title=A closely packed system of low-mass, low-density planets transiting Kepler-11 | last1=Lissauer | first1=Jack J. | last2=Fabrycky | first2=Daniel C. | last3=Ford | first3=Eric B. | last4=Borucki | first4=William J. | last5=Fressin | first5=Francois | last6=Marcy | first6=Geoffrey W. | last7=Orosz | first7=Jerome A. | last8=Rowe | first8=Jason F. | last9=Torres | first9=Guillermo | last10=Welsh | first10=William F. | last11=Batalha | first11=Natalie M. | last12=Bryson | first12=Stephen T. | last13=Buchhave | first13=Lars A. | last14=Caldwell | first14=Douglas A. | last15=Carter | first15=Joshua A. | last16=Charbonneau | first16=David | last17=Christiansen | first17=Jessie L. | last18=Cochran | first18=William D. | last19=Desert | first19=Jean-Michel | last20=Dunham | first20=Edward W. | last21=Fanelli | first21=Michael N. | last22=Fortney | first22=Jonathan J. | last23=Gautier III | first23=Thomas N. | last24=Geary | first24=John C. | last25=Gilliland | first25=Ronald L. | last26=Haas | first26=Michael R. | last27=Hall | first27=Jennifer R. | last28=Holman | first28=Matthew J. | last29=Koch | first29=David G. | last30=Latham | first30=David W. | s2cid=4388001 | display-authors=1 | journal=Nature | volume=470 | issue=7332 | pages=53–58 | year=2011 | arxiv=1102.0291 | bibcode=2011Natur.470...53L | doi=10.1038/nature09760 | pmid=21293371 }}</ref> With a spectral type of G6V, the star is somewhat cooler than the Sun. All the planets are more massive than Earth, and all have low densities; and all but one are closer to Kepler-11 than [[Mercury (planet)|Mercury]] is to the Sun.<ref name="Lissauer2013_Kepler-11">{{cite journal | title=All Six Planets Known to Orbit Kepler-11 Have Low Densities | last1=Lissauer | first1=Jack J. | last2=Jontof-Hutter | first2=Daniel | last3=Rowe | first3=Jason F. | last4=Fabrycky | first4=Daniel C. | last5=Lopez | first5=Eric D. | last6=Agol | first6=Eric | last7=Marcy | first7=Geoffrey W. | last8=Deck | first8=Katherine M. | last9=Fischer | first9=Debra A. | last10=Fortney | first10=Jonathan J. | last11=Howell | first11=Steve B. | last12=Isaacson | first12=Howard | last13=Jenkins | first13=Jon M. | last14=Kolbl | first14=Rea | last15=Sasselov | first15=Dimitar | last16=Short | first16=Donald R. | last17=Welsh | first17=William F. | display-authors=1 | journal=The Astrophysical Journal | volume=770 | issue=2 | at=131 | year=2013 | arxiv=1303.0227 | bibcode=2013ApJ...770..131L | bibcode-access=free | doi=10.1088/0004-637X/770/2/131 | doi-access=free }}</ref><ref name="Lissauer2011_Kepler-11" /> The naked-eye star [[16 Cygni]], a triple star approximately 70 light-years from Earth composed two Sun-like stars and a [[red dwarf]],<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 |year=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 }}</ref> contains a planet orbiting one of the sun-like stars, found due to variations in the star's radial velocity.<ref name=truemass>{{cite journal |title=Analysis of the motion of an extrasolar planet in a binary system |author=E. Plávalová |author2=N. A. Solovaya |arxiv=1212.3843 |journal=Astronomy & Astrophysics |year=2013 |bibcode=2013AJ....146..108P |doi=10.1088/0004-6256/146/5/108 |volume=146 |issue=5 |pages=108|s2cid=118629538 }}</ref> [[Gliese 777]], another naked-eye multiple star system containing a yellow star and a red dwarf, also contains a planet. The planet is somewhat similar to [[Jupiter]], but with slightly more mass and a more eccentric orbit.<ref name="Naef2003">{{cite journal |title=The ELODIE survey for northern extra-solar planets II. A Jovian planet on a long-period orbit around GJ 777 A |last1=Naef |first1=D. |last2=Mayor |first2=M. |last3=Korzennik |first3=S. G. |last4=Queloz |first4=D. |last5=Udry |first5=S. |last6=Nisenson |first6=P. |last7=Noyes |first7=R. W. |last8=Brown |first8=T. M. |last9=Beuzit |first9=J. L. | display-authors=1 |journal=Astronomy and Astrophysics |volume=410 |issue=3 |pages=1051–1054 |year=2003 |arxiv=astro-ph/0306586 |bibcode=2003A&A...410.1051N |doi=10.1051/0004-6361:20031341|s2cid=14853884 }}</ref><ref name="Vogt2005">{{cite journal |title=Five New Multicomponent Planetary Systems |last1=Vogt |first1=Steven S. |last2=Butler |first2=R. Paul |last3=Marcy |first3=Geoffrey W. |last4=Fischer |first4=Debra A. |last5=Henry |first5=Gregory W. |last6=Laughlin |first6=Greg |last7=Wright |first7=Jason T. |last8=Johnson |first8=John A. | display-authors=1 |journal=The Astrophysical Journal |volume=632 |issue=1 |pages=638–658 |year=2005 |doi=10.1086/432901 |bibcode=2005ApJ...632..638V|s2cid=16509245 |url=https://authors.library.caltech.edu/36250/1/0004-637X_632_1_638.pdf |archive-url=https://web.archive.org/web/20180722000634/https://authors.library.caltech.edu/36250/1/0004-637X_632_1_638.pdf |archive-date=2018-07-22 |url-status=live }}</ref> The [[Kepler-22]] system is also notable for having the most Earth-like exoplanet when it was discovered in 2011.<ref name="bbc20111205">{{cite news |url=https://www.bbc.co.uk/news/science-environment-16040655 |title=Kepler 22-b: Earth-like planet confirmed |date=5 December 2011 |publisher=[[BBC]] |access-date=6 December 2011}}</ref>