View source for WASP-2

{{Short description|Multiple star system in the constellation Delphinus}}
{{Starbox begin 
| name = WASP-2
}} 
{{Starbox observe 2s
| epoch = J2000.0
| constell = [[Delphinus (constellation)|Delphinus]]
| component1 = A<ref name="binary" />
| ra1 = {{RA|20|30|54.1279}}<ref name="Gaia DR2"/>
| dec1 = {{DEC|+06|25|46.338}}<ref name="Gaia DR2"/>
| appmag_v1 = +11.98<ref name="SIMBAD" />
| component2 = C{{refn|group=a|The secondary star is identified with a "C" suffix so as to not confuse it with the planetary designation suffix "b".<ref name=binary/>}}
| ra2 = ~{{RA|20|30|54}}<ref name="binary" />
| dec2 = ~{{DEC|+06|25|46}}<ref name="binary" />
| appmag_v2 = 15.38<ref name="binary" />
}} 
{{Starbox orbit
| reference = <ref name=Quarles2019/>
| primary = WASP-2A
| name = WASP-2B
| period = <!--Period (in years)-->
| period_unitless = <!--Period (no units provided by template)-->
| axis = 106
| axis_unitless = <!--Semimajor axis (no units provided by template)-->
| eccentricity = <!--Eccentricity-->
| inclination = <!--Inclination (in degrees)-->
| node = <!--Longitude of node (in degrees)-->
| periastron = <!--Periastron epoch-->
| periarg = <!--Argument of periastron (in degrees), secondary -->
| periarg_primary = <!--Argument of periastron (in degrees), primary -->
| k1 = <!-- Velocity semi-amplitude (SB1, or primary in SB2), in km/s -->
| k2 = <!-- Velocity semi-amplitude (secondary in SB2), in km/s -->
}}
{{Starbox character 
| class = K1.5V + K2-M3<ref>{{citation|arxiv=1507.01938|title=A Lucky Imaging search for stellar companions to transiting planet host stars|year=2015|doi=10.1051/0004-6361/201424091|last1=Wöllert|first1=Maria|last2=Brandner|first2=Wolfgang|last3=Bergfors|first3=Carolina|last4=Henning|first4=Thomas|journal=Astronomy & Astrophysics|volume=575|pages=A23|bibcode=2015A&A...575A..23W|s2cid=119250579}}</ref>
| appmag_1_passband = B
| appmag_1 = ~13<ref name="SIMBAD" />
| appmag_2_passband = V
| appmag_2 = ~11.98<ref name="SIMBAD" />
| appmag_3_passband = J
| appmag_3 = 10.166±0.027<ref name="SIMBAD" />
| appmag_4_passband = H
| appmag_4 = 9.752±0.026<ref name="SIMBAD" />
| appmag_5_passband = K
| appmag_5 = 9.632±0.024<ref name="SIMBAD" />
| variable = 
}} 
{{Starbox astrometry 
| radial_v =
| prop_mo_ra = {{val|5.936|0.101}}<ref name="Gaia DR2"/>
| prop_mo_dec = {{val|−48.279|0.082}}<ref name="Gaia DR2"/>
| parallax = 6.4980
| p_error = 0.0686
| parallax_footnote = <ref name="Gaia DR2"/>
| absmag_v = 
}} 
{{Starbox detail
|source=<ref name=Southworth2020>{{citation|arxiv=2001.08225|title=A multiplicity study of transiting exoplanet host stars. II.Revised properties of transiting planetary systems with companions|year=2020|doi=10.1051/0004-6361/201937334|last1=Southworth|first1=J.|last2=Bohn|first2=A. J.|last3=Kenworthy|first3=M. A.|last4=Ginski|first4=C.|last5=Mancini|first5=L.|journal=Astronomy & Astrophysics|volume=A74|page=635|bibcode=2020A&A...635A..74S|s2cid=210860775}}</ref>
|component1= WASP-2A
|component2= WASP-2B
| age_gyr=7.6{{±|2.5|3.3}}
| metal = 
| mass = 0.843{{±|0.033}}
|mass2=0.48<ref name="binary" />
| radius = 0.821{{±|0.013}}
| rotation = 
| luminosity = 
| temperature = 5170{{±|60}}
| temperature2=3523{{±|28|19}}
| 

}} 
{{Starbox catalog 
| names = [[Guide Star Catalog|GSC]] 00522-01199, [[SuperWASP|1SWASP]] J203054.12+062546.4, USNO-B1.0 0964-00543604, [[2MASS]] J20305413+0625463, UCAC2 34018636, Gaia DR2 1748596020745038208, V357 Del
}}
{{Starbox reference
| Simbad = WASP-2
| EPE = WASP-2
}}
{{Starbox end}}

'''WASP-2''' is a [[binary star]] system in the [[Delphinus]] [[constellation]] located about 500 light-years away.<ref name="SIMBAD">{{cite simbad | title =WASP-2  | accessdate=2009-05-04 }}</ref>
The primary is [[Apparent magnitude|magnitude]] 12 [[orange dwarf]] [[star]], orbited by [[red dwarf]] star on wide orbit.<ref name=Quarles2019>{{citation|arxiv=1912.11019|title=Orbital stability of circumstellar planets in binary systems|year=2020|doi=10.3847/1538-3881/ab64fa|last1=Quarles|first1=Billy|last2=Li|first2=Gongjie|last3=Kostov|first3=Veselin|last4=Haghighipour|first4=Nader|journal=The Astronomical Journal|volume=159|issue=3|page=80|bibcode=2020AJ....159...80Q|s2cid=209444271 |doi-access=free }}</ref><ref>[https://ui.adsabs.harvard.edu/abs/2005PASJ...57...83T/abstract Precise Differential Analysis of Stellar Metallicities: Application to Solar Analogs Including 16 Cyg A and B]</ref> The star system shows an infrared excess noise of unknown origin.<ref>{{citation|arxiv=1202.2799|year=2012|doi=10.1086/665043|last1=Sada|first1=Pedro V.|last2=Deming|first2=Drake|last3=Jennings|first3=Donald E.|last4=Jackson|first4=Brian k.|last5=Hamilton|first5=Catrina M.|last6=Fraine|first6=Jonathan|last7=Peterson|first7=Steven W.|last8=Haase|first8=Flynn|last9=Bays|first9=Kevin|last10=Lunsford|first10=Allen|last11=o'Gorman|first11=Eamon|title=Extrasolar Planet Transits Observed at Kitt Peak National Observatory|journal=Publications of the Astronomical Society of the Pacific|volume=124|issue=913|pages=212–229|bibcode=2012PASP..124..212S|s2cid=29665395}}</ref>

==Planetary system==
This star has one [[extrasolar planet]] [[WASP-2b]], detected by the [[SuperWASP]] project in 2006.<ref name="Cameron2007"/>

{{OrbitboxPlanet begin
|table_ref=<ref name=Southworth2020/>
}}
{{OrbitboxPlanet
| exoplanet = [[WASP-2b|b]]
| mass = 0.882{{±|0.027}}
|radius=1.06{{±|0.024}}
| period = 2.15222144 (± 4e-07)
| semimajor = 0.0308{{±|0.0004}}
| eccentricity = 0
}}
{{Orbitbox end}}

==Binary star==
In 2008 a study was undertaken of fourteen stars with exoplanets that were originally discovered using the [[Methods of detecting extrasolar planets#Transit method|transit method]] through relatively small telescopes. These systems were re-examined with the {{convert|2.2|m|in|abbr=on}} [[reflector telescope]] at the [[Calar Alto Observatory]] in [[Spain]]. This star system, along with two others, was determined to be a previously unknown [[binary star]] system. The previously unknown secondary star is a dim [[apparent magnitude|magnitude]] 15 [[Stellar classification#Class M|M-type]] star separated by about 111 [[Astronomical unit|AU]] from the primary, appearing offset from the primary by about one arc second in the images. This discovery resulted in a recalculation of parameters for both the planet and the primary star.<ref name=binary>{{cite journal
| url=http://www.mpia.de/homes/henning/Publications/daemgen.pdf
| title=Binarity of transit host stars - Implications for planetary parameters
| date=2009
| volume=498
| pages=567–574 
| author=Daemgen
| journal=[[Astronomy and Astrophysics]]
| doi=10.1051/0004-6361/200810988
| last2=Hormuth
| first2=F.
| last3=Brandner
| first3=W.
| last4=Bergfors
| first4=C.
| last5=Janson
| first5=M.
| last6=Hippler
| first6=S.
| last7=Henning
| first7=T.
| bibcode=2009A&A...498..567D
| display-authors=1
| issue=2|arxiv = 0902.2179 | s2cid=9893376
}}</ref>

The re-examination of the WASP-2 spectrum in 2015, have resulted in the measurement of stellar companion temperature equal to 3513{{±|28}} [[Kelvin|K]], and angular separation of 0.73 arc second.<ref>{{citation|arxiv=1510.08062|year=2015|doi=10.1088/0004-637X/814/2/148|last1=Piskorz|first1=Danielle|last2=Knutson|first2=Heather A.|last3=Ngo|first3=Henry|last4=Muirhead|first4=Philip S.|last5=Batygin|first5=Konstantin|last6=Crepp|first6=Justin R.|last7=Hinkley|first7=Sasha|last8=Morton|first8=Timothy D.|title=Friends of Hot Jupiters. III. An Infrared Spectroscopic Search for Low-Mass Stellar Companions|journal=The Astrophysical Journal|volume=814|issue=2|page=148|bibcode=2015ApJ...814..148P|s2cid=11525988}}</ref>

==See also==
* [[SuperWASP]]
* [[WASP-1]]

==Notes==
{{reflist|group=a}}

==References==
{{Reflist|refs=

<ref name="Cameron2007">{{cite journal | title=WASP-1b and WASP-2b: two new transiting exoplanets detected with SuperWASP and SOPHIE | last1=Cameron | first1=A. Collier | last2=Bouchy | first2=F. | last3=Hébrard | first3=G. | last4=Maxted | first4=P. | last5=Pollacco | first5=D. | last6=Pont | first6=F. | last7=Skillen | first7=I. | last8=Smalley | first8=B. | last9=Street | first9=R. A. | display-authors=1 | journal=[[Monthly Notices of the Royal Astronomical Society]] | volume=375 | issue=3 | pages=951–957 | date=2007 | arxiv=astro-ph/0609688 | bibcode=2007MNRAS.375..951C | doi=10.1111/j.1365-2966.2006.11350.x | doi-access=free | s2cid=735515 }}</ref>

<ref name="Gaia DR2">{{Cite Gaia DR2|1748596020745038208}}</ref>

}}

==External links==
* {{cite web
| url=http://media4.obspm.fr/exoplanets/base/etoile.php?nom=WASP-2
| title=WASP-2
| work=Exoplanets
| accessdate=2009-05-04
| archive-date=2012-04-01
| archive-url=https://web.archive.org/web/20120401192620/http://media4.obspm.fr/exoplanets/base/etoile.php?nom=WASP-2
| url-status=dead
}}

{{Sky|20|30|54.130|+|06|25|46.37|470}}

{{Stars of Delphinus}}

{{DEFAULTSORT:WASP-2}}
[[Category:Delphinus]]
[[Category:Planetary transit variables]]
[[Category:Planetary systems with one confirmed planet]]
[[Category:Binary stars]]
[[Category:K-type main-sequence stars]]
[[Category:Wide Angle Search for Planets|2]]
[[Category:2MASS objects|J20305413+0625463]]