XO-2
{{Short description|Binary star system in the constellation Lynx}}
{{other uses}}
{{Starbox begin
| name = XO-2
}}
{{Starbox observe 2s
| epoch = J2000
| constell = Lynx
| component1 = XO-2S
| dec1 = {{DEC|+50|13|03.2554}}
| appmag_v1 = {{val|11.12|0.03}}
| component2 = XO-2N
| dec2 = {{DEC|+50|13|32.9206}}
| appmag_v2 = {{val|11.18|0.03}}
}}
{{Starbox character
}}
{{Starbox astrometry
| component1 = XO-2S
| radial_v = {{val|46.94|0.27}}
| prop_mo_ra = {{val|−29.308|(15)}}
| prop_mo_dec = {{val|−154.233|(13)}}
| parallax = 6.6721
| p_error = 0.0151
| component2 = XO-2N
| radial_v2 = {{val|47.45|0.44}}
| prop_mo_ra2 = {{val|−29.552|(15)}}
| prop_mo_dec2 = {{val|−154.227|(11)}}
| parallax2 = 6.6588
| p_error2 = 0.0158
}}
{{Starbox detail
| component1 = XO-2S
| mass = {{val|0.9624|0.0073}}
| radius = {{val|1.011|0.019}}
| gravity = {{val|4.420|0.094}}
| luminosity = {{val|0.79|0.14}}
| temperature = {{val|5325|37|fmt=commas}}
| metal_fe = {{val|0.32|0.08}}
| rotation = {{val|26.0|0.6|ul=d}}
| rotational_velocity = {{val|1.5|0.3}}
| age_gyr = {{val|7.1|2.5|2.9}}
| component2 = XO-2N
| mass2 = {{val|0.96|0.05}}
| radius2 = {{val|0.998|0.033|0.032}}
| gravity2 = {{val|4.43|0.10}}
| luminosity2 = {{val|0.70|0.04}}
| temperature2 = {{val|5290|18|fmt=commas}}
| metal_fe2 = {{val|0.37|0.07}}
| rotation2 = {{val|41.6|1.1|ul=d}}
| rotational_velocity2 = {{val|1.07|0.09}}
| age_gyr2 = {{val|7.8|1.2|1.3}}
}}
{{Starbox catalog
| component1 = XO-2S
| names1 = {{odlist | 2MASS=J07480748+5013032 | GSC=03413-00210 | LSPM=J0748+5013S | TYC=3413-210-1 }}
| component2 = XO-2N
| names2 = {{odlist | 2MASS=J07480647+5013328 | BD=+50 1471 | GSC=03413-00005 | LSPM=J0748+5013N | TIC=356473034 | TOI=1720 | TYC=3413-5-1 }}
}}
{{Starbox reference
| Simbad = XO-2S | sn=XO-2S
| Simbad2 = XO-2N | sn2=XO-2N
| NSTED = XO-2
}}
{{Starbox end}}
XO-2 is a binary star system about {{convert|490|ly|pc|lk=on|abbr=off}} away in the constellation Lynx. It consists of two components, XO-2N and XO-2S, both of which host planetary systems.
Star system
This system is unusual in that the stars are not typically referred to as components A & B, but are designated based on their positions in the sky: XO-2N is the northern star and XO-2S is the southern star.
Both of the stars are slightly cooler than the Sun and are nearly identical to each other. The system has a magnitude of 11 and cannot be seen with the naked eye but is visible through a small telescope. These stars are also notable for their large proper motions.
XO-2N and XO-2S have a separation of approximately {{formatnum:4600}} AU.
Planetary systems
There is one confirmed exoplanet orbiting XO-2N. XO-2Nb, which is classified as a hot Jupiter, was discovered by the XO Telescope using the transit method around XO-2N in 2007. It was initially the only known planet in the system and was referred to as XO-2b. A long-period variation in the radial velocity of XO-2N was detected in 2015, which could be explained by either a second planet or a stellar activity cycle. The stellar activity explanation is considered more likely, and is further supported by a 2024 study.
Two planets were reported to orbit around XO-2S in 2014 using the radial velocity method. One of them is Jupiter-mass and another has a mass comparable to Saturn. A 2024 study found evidence for a third, super-Jupiter mass planet around XO-2S.
{{OrbitboxPlanet begin
| name = XO-2N
| table_ref = {{Efn|1=Mass and eccentricity: Damasso et al. 2015
Other properties: Wang et al. (2025)}}
}}
{{OrbitboxPlanet
| exoplanet = b
| mass = {{val|0.597|0.021}}
| radius = {{val|1.033|0.023}}
| period = {{val|2.615859719|(54)}}
| semimajor = {{val|0.03668|(9)}}
| eccentricity = <0.006
| inclination = {{val|87.47|0.37}}
}}
{{Orbitbox end}}
{{OrbitboxPlanet begin
| name = XO-2S
}}
{{OrbitboxPlanet
| exoplanet = b
| mass = {{val|0.26|0.01|p=≥}}
| period = {{val|18.220|0.001}}
| semimajor = {{val|0.1347|0.0025}}
| eccentricity = {{val|0.15|0.02}}
}}
{{OrbitboxPlanet
| exoplanet = c
| mass = {{val|1.38|0.05|p=≥}}
| period = {{val|120.059|0.013}}
| semimajor = {{val|0.4737|0.0085|0.0088}}
| eccentricity = {{val|0.149|0.006}}
}}
{{OrbitboxPlanet
| exoplanet = d
| mass = {{val|3.71|1.2|0.51|p=≥}}
| period = {{val|4696|1133|489|fmt=commas}}
| semimajor = {{val|5.46|0.85|0.40}}
| eccentricity = {{val|0.091|0.028|0.018}}
}}
{{Orbitbox end}}
See also
Notes
{{notelist}}
References
{{Reflist|refs=
{{cite DR3|934346740559239296}}
{{cite DR3|934346809278715776}}
{{cite simbad | title=TYC 3413-210-1 |access-date=2018-01-28}}
{{cite simbad | title=TYC 3413-5-1 |access-date=2018-01-28}}
{{cite journal |last1=Ruggieri |first1=A. |last2=Desidera |first2=S. |display-authors=etal |date=April 2024 |title=The GAPS Programme at TNG. LIII. New insights on the peculiar XO-2 system |journal=Astronomy & Astrophysics |volume=684 |issue= |pages=A116 |doi=10.1051/0004-6361/202348042 |arxiv=2401.17876 |bibcode=2024A&A...684A.116R}}
}}
Further reading
- {{cite journal | title=The Transit Light Curve Project. XII. Six Transits of the Exoplanet XO-2b | last1=Fernandez | first1=Jose M. | last2=Holman | first2=Matthew J. | last3=Winn | first3=Joshua N. | last4=Torres | first4=Guillermo | last5=Shporer | first5=Avi | last6=Mazeh | first6=Tsevi | last7=Esquerdo | first7=Gilbert A. | last8=Everett | first8=Mark E. | display-authors=1 | journal=The Astronomical Journal | volume=137 | issue=6 | pages=4911–4916 | year=2009 | arxiv=0903.2687 | bibcode=2009AJ....137.4911F | bibcode-access=free | doi=10.1088/0004-6256/137/6/4911 | doi-access=free | s2cid=7113991 }}
- {{cite journal | title=XO-2b: a Prograde Planet with a Negligible Eccentricity and an Additional Radial Velocity Variation | last1=Narita | first1=Norio | last2=Hirano | first2=Teruyuki | last3=Sato | first3=Bun’ei | last4=Harakawa | first4=Hiroki | last5=Fukui | first5=Akihiko | last6=Aoki | first6=Wako | last7=Tamura | first7=Motohide | display-authors=1 | journal=Publications of the Astronomical Society of Japan | volume=63 | issue=6 | pages=L67–L71 | year=2011 | arxiv=1110.6136 | bibcode=2011PASJ...63L..67N | doi=10.1093/pasj/63.6.l67 | doi-access=free | s2cid=119269227 }}
- {{cite journal | title=Gran Telescopio Canarias OSIRIS transiting exoplanet atmospheric survey: detection of potassium in XO-2b from narrowband spectrophotometry | last1=Sing | first1=D. K. | last2=Désert | first2=J.-M. | last3=Fortney | first3=J. J. | last4=Lecavelier Des Etangs | first4=A. | last5=Ballester | first5=G. E. | last6=Cepa | first6=J. | last7=Ehrenreich | first7=D. | last8=López-Morales | first8=M. | last9=Pont | first9=F. | last10=Shabram | first10=M. | last11=Vidal-Madjar | first11=A. | display-authors=1 | journal=Astronomy and Astrophysics | volume=527 | page= | article-number=A73 | year=2011 | arxiv=1008.4795 | bibcode=2011A&A...527A..73S | bibcode-access=free | doi=10.1051/0004-6361/201015579 | doi-access=free | s2cid=56545385 }}
External links
- NASA PlanetQuest: [https://web.archive.org/web/20090419230513/http://planetquest.jpl.nasa.gov/news/Gl436.cfm Planet race heats up: 1 month, 32 discoveries]
- {{cite web
| url=http://media4.obspm.fr/exoplanets/base/etoile.php?nom=XO-2
| title=XO-2
| work=Exoplanets
| access-date=2009-04-28
| archive-date=2016-03-03
| archive-url=https://web.archive.org/web/20160303190408/http://media4.obspm.fr/exoplanets/base/etoile.php?nom=XO-2
| url-status=dead
}}
{{Sky|07|48|06.468|+|50|13|32.96|486}}
{{Stars of Lynx}}
{{DEFAULTSORT:XO-2 (star)}}
Category:K-type main-sequence stars
Category:Planetary transit variables