Editing Corona Borealis (section)

=== Extrasolar planetary systems ===
[[Extrasolar planets]] have been confirmed in five star systems, four of which were found by the [[methods of detecting exoplanets#Radial velocity|radial velocity]] method. The spectrum of [[Epsilon Coronae Borealis]] was analysed for seven years from 2005 to 2012, revealing a planet around 6.7&nbsp;times as massive as [[Jupiter]] ({{Jupiter mass|link=y}}) orbiting every 418&nbsp;days at an average distance of around 1.3&nbsp;AU.<ref name="lee 2012">{{cite journal|author1=Lee, B.-C. |author2=Han, I. |author3=Park, M.-G. |author4=Mkrtichian, D. E. |author5=Kim, K.-M. |date=2012|title=A planetary companion around the K giant ɛ Corona Borealis|journal=Astronomy & Astrophysics|volume=546|id=A5|pages=5|bibcode=2012A&A...546A...5L|doi=10.1051/0004-6361/201219347|arxiv = 1209.1187 |s2cid=55260442 }}</ref> Epsilon itself is a {{Solar mass|1.7}} orange giant of spectral type K2III that has swollen to {{Solar radius|21}} and {{Solar luminosity|151}}.<ref name=aj135_1_209>{{cite journal | last1=Massarotti | first1=Alessandro | last2=Latham | first2=David W. | last3=Stefanik | first3=Robert P. | last4=Fogel | first4=Jeffrey | s2cid=121883397 | title=Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity | journal=The Astronomical Journal | volume=135 | issue=1 | pages=209–31 |date=January 2008 | doi=10.1088/0004-6256/135/1/209 | bibcode=2008AJ....135..209M | doi-access=free }}</ref> [[Kappa Coronae Borealis]] is a spectral type K1IV orange subgiant nearly twice as massive as the Sun; around it lies a dust debris disk,<ref name="Pawellek 2014"/> and one planet with a period of 3.4&nbsp;years.<ref name="PASJ">{{cite journal |journal=Publications of the Astronomical Society of Japan | volume = 64 |issue = 6 |id=135 |pages= 14 |title=Substellar Companions to Seven Evolved Intermediate-Mass Stars |arxiv=1207.3141 |year=2012 |author1=Sato, Bun'ei |author2=Omiya, Masashi |author3=Harakawa, Hiroki |author4=Izumiura, Hideyuki |author5=Kambe, Eiji |author6=Takeda, Yoichi |author7=Yoshida, Michitoshi |author8=Itoh, Yoichi |author9=Ando, Hiroyasu |author10=Kokubo, Eiichiro |author11=Ida, Shigeru |bibcode = 2012PASJ...64..135S |doi = 10.1093/pasj/64.6.135| s2cid = 119197073 }}</ref> This planet's mass is estimated at {{Jupiter mass|2.5|link=y}}. The dimensions of the debris disk indicate it is likely there is a second substellar companion.<ref name=Bonsor13>{{cite journal |author1=Bonsor, Amy |author2=Kennedy, Grant M. |author3=Crepp, Justin R. |author4=Johnson, John A. |author5=Wyatt, Mark C. |author6=Sibthorpe, Bruce |author7=Su, Kate Y. L. |year=2013 |title=Spatially Resolved Images of Dust Belt(s) Around the Planet-hosting Subgiant κ CrB |journal=[[Monthly Notices of the Royal Astronomical Society|MNRAS]] |volume=431 |issue= 4|pages=3025–3035 |doi=10.1093/mnras/stt367 |doi-access=free |arxiv = 1302.7000 |bibcode = 2013MNRAS.431.3025B |s2cid=27703182 }}</ref> [[Omicron Coronae Borealis]] is a K-type [[Red clump|clump giant]] with one confirmed planet with a mass of {{Jupiter mass|0.83}} that orbits every 187&nbsp;days—one of the two least massive planets known around clump giants.<ref name="PASJ"/> [[HD 145457]] is an orange giant of spectral type K0III found to have one planet of {{Jupiter mass|2.9}}. Discovered by the Doppler method in 2010, it takes 176&nbsp;days to complete an orbit.<ref name="sato 2010">{{cite journal|author1=Sato, Bun'ei |author2=Omiya, Masashi |author3=Liu, Yujuan |author4=Harakawa, Hiroki |author5=Izumiura, Hideyuki |author6=Kambe, Eiji |author7=Toyota, Eri |author8=Murata, Daisuke |author9=Lee, Byeong-Cheol |author10=Masuda, Seiji |author11=Takeda, Yoichi |author12=Yoshida, Michitoshi |author13=Itoh, Yoichi |author14=Ando, Hiroyasu |author15=Kokubo, Eiichiro |author16=Ida, Shigeru |author17=Zhao, Gang |author18=Han, Inwoo |date=2010|title=Substellar Companions to Evolved Intermediate-Mass Stars: HD 145457 and HD 180314|journal=Publications of the Astronomical Society of Japan|volume=62|issue=4|pages=1063–69|bibcode=2010PASJ...62.1063S|doi=10.1093/pasj/62.4.1063|arxiv = 1005.2860 |s2cid=119113950 }}</ref> [[XO-1]] is a magnitude 11 [[G-type main-sequence star|yellow main-sequence star]] located approximately {{convert|172|pc|ly|disp=output number only}} light-years away,<ref name="Torres2008">{{cite journal | title=Improved Parameters for Extrasolar Transiting Planets | last1=Torres | first1=Guillermo | last2=Winn | first2=Joshua N. | last3=Holman | first3=Matthew J. | journal=The Astrophysical Journal | volume=677 | issue=2 | pages=1324–42 | year=2008 | arxiv=0801.1841 | bibcode=2008ApJ...677.1324T | doi=10.1086/529429 | s2cid=12899134 }}</ref> of spectral type G1V with a mass and radius similar to the Sun. In 2006 the [[hot Jupiter]] exoplanet [[XO-1b]] was discovered orbiting XO-1 by the [[Methods of detecting exoplanets#Transit photometry|transit method]] using the [[XO Telescope]]. Roughly the size of Jupiter, it completes an orbit around its star every three days.<ref name="McCullough2006">{{cite journal | title=A Transiting Planet of a Sun-like Star | last1=McCullough | first1=P. R. | last2=Stys | first2=J. E. | last3=Valenti | first3=Jeff A. | last4=Johns-krull | first4=C. M. | last5=Janes | first5=K.A. | last6=Heasley | first6=J. N. | last7=Bye | first7=B. A. | last8=Dodd | first8=C. | last9=Fleming | first9=S. W. | last10=Pinnick | first10=A. | last11=Bissinger | first11=R. | last12=Gary | first12=B. L. | last13=Howell | first13=P. J. | last14=Vanmunster | first14=T. | journal=The Astrophysical Journal | volume=648 | issue=2 | pages=1228–38 | year=2006 | arxiv=astro-ph/0605414 | bibcode=2006ApJ...648.1228M | doi=10.1086/505651| s2cid=8100425 }}</ref><!-- cites previous 1.5 sentences -->

The discovery of a Jupiter-sized planetary companion was announced in 1997 via analysis of the radial velocity of Rho Coronae Borealis, a yellow main sequence star and [[Solar analog]] of spectral type G0V,<ref name="Belle">{{cite journal | author=van Belle, Gerard T.  | author2=von Braun, Kaspar  | title=Directly Determined Linear Radii and Effective Temperatures of Exoplanet Host Stars | journal=[[The Astrophysical Journal]] | volume=694 | issue=2 | date=2009 | pages=1085–98| doi=10.1088/0004-637X/694/2/1085 | bibcode=2009ApJ...694.1085V|arxiv = 0901.1206 | s2cid=18370219 }}</ref> around 57 light-years distant from Earth.<ref>{{cite journal|author1=Noyes, Robert W. |author2=Jha, Saurabh |author3=Korzennik, Sylvain G. |author4=Krockenberger, Martin |author5=Nisenson, Peter |author6=Brown, Timothy M. |author7=Kennelly, Edward J. |author8=Horner, Scott D. |title=A Planet Orbiting the Star ρ Coronae Borealis|year=1997|journal=The Astrophysical Journal|volume=483|issue=2|pages=L111–14|doi=10.1086/310754|bibcode=1997ApJ...483L.111N|arxiv = astro-ph/9704248 |s2cid=115606006 }}</ref> More accurate measurement of data from the [[Hipparcos]] satellite subsequently showed it instead to be a low-mass star somewhere between 100 and 200 times the mass of Jupiter.<ref name="ReffertQuirrenbach">{{cite journal|author1=Reffert, S. |author2=Quirrenbach, A. |title=Mass constraints on substellar companion candidates from the re-reduced Hipparcos intermediate astrometric data: nine confirmed planets and two confirmed brown dwarfs|year=2011|journal=Astronomy & Astrophysics|volume=527|pages=A140|doi=10.1051/0004-6361/201015861|bibcode=2011A&A...527A.140R|arxiv=1101.2227|s2cid=54986291 }}</ref> Possible stable planetary orbits in the [[Circumstellar habitable zone|habitable zone]] were calculated for the binary star [[Eta Coronae Borealis]],<ref>{{cite journal|last=Benest|first=D.|date=1996|title= Planetary orbits in the elliptic restricted problem. III. The η Coronae Borealis system.|journal=Astronomy and Astrophysics|volume=314|pages=983–88|bibcode=1996A&A...314..983B}}</ref> which is composed of two stars—yellow main sequence stars of spectral type G1V and G3V respectively—similar in mass and spectrum to the Sun.<ref name=kalereta>{{cite web| first1=James B. | last1=Kaler | title=Eta Coronae Borealis | work=Stars | publisher=University of Illinois | url=http://stars.astro.illinois.edu/sow/etacrb.html | date =22 June 2012 | access-date=16 March 2015}}</ref> No planet has been found, but a brown dwarf companion about 63 times as massive as Jupiter with a spectral type of L8 was discovered at a distance of 3640&nbsp;AU from the pair in 2001.<ref name="brown">{{cite journal | title=Brown Dwarf Companions to G-Type Stars. I. Gliese 417B and Gliese 584C | journal=The Astronomical Journal | volume=121 | issue=6 | pages=3235–3253 |author1=Kirkpatrick, J. Davy |author2=Dahn, Conard C. |author3=Monet, David G. |author4=Reid, I. Neill |author5=Gizis, John E. |author6=Liebert, James |author7=Burgasser, Adam J. | year=2001 | arxiv=astro-ph/0103218 |bibcode=2001AJ....121.3235K |doi = 10.1086/321085 | s2cid=18515414 }}</ref>