XO-2

Binary star system in the constellation Lynx
XO-2
Observation data
Epoch J2000      Equinox J2000
Constellation Lynx[1]
XO-2S
Right ascension 07h 48m 07.4814s[2]
Declination +50° 13′ 03.2554″[2]
Apparent magnitude (V) 11.12±0.03[3]
XO-2N
Right ascension 07h 48m 06.4723s[4]
Declination +50° 13′ 32.9206″[4]
Apparent magnitude (V) 11.18±0.03[3]
Characteristics
Spectral type K0V + K0V[3]
Astrometry
XO-2S
Radial velocity (Rv)46.94±0.27[2] km/s
Proper motion (μ) RA: −29.308(15) mas/yr[2]
Dec.: −154.233(13) mas/yr[2]
Parallax (π)6.6721 ± 0.0151 mas[2]
Distance489 ± 1 ly
(149.9 ± 0.3 pc)
Absolute magnitude (MV)5.74[5]
XO-2N
Radial velocity (Rv)47.45±0.44[4] km/s
Proper motion (μ) RA: −29.552(15) mas/yr[4]
Dec.: −154.227(11) mas/yr[4]
Parallax (π)6.6588 ± 0.0158 mas[4]
Distance490 ± 1 ly
(150.2 ± 0.4 pc)
Absolute magnitude (MV)5.74[5]
Details[6]
XO-2S
Mass0.98±0.05 M☉
Radius1.02+0.09
−0.06 R☉
Luminosity0.79±0.14 L☉
Surface gravity (log g)4.420±0.094 cgs
Temperature5,325±37 K
Metallicity [Fe/H]0.32±0.08 dex
Rotation26.0±0.6 d
Rotational velocity (v sin i)1.5±0.3 km/s
Age7.1+2.5
−2.9 Gyr
XO-2N
Mass0.96±0.05 M☉
Radius0.998+0.033
−0.032 R☉
Luminosity0.70±0.04 L☉
Surface gravity (log g)4.43±0.10 cgs
Temperature5,290±18 K
Metallicity [Fe/H]0.37±0.07 dex
Rotation41.6±1.1 d
Rotational velocity (v sin i)1.07±0.09 km/s
Age7.8+1.2
−1.3 Gyr
Other designations
XO-2S: LSPM J0748+5013S, TYC 3413-210-1, GSC 03413-00210, 2MASS J07480748+5013032[7]
XO-2N: BD+50 1471, LSPM J0748+5013N, TOI-1720, TIC 356473034, TYC 3413-5-1, GSC 03413-00005, 2MASS J07480647+5013328[8]
Database references
SIMBADXO-2S
XO-2N

XO-2 is a binary star system about 490 light-years (150 parsecs) away in the constellation Lynx. It consists of two components, XO-2N and XO-2S, both of which host planetary systems.[9]

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.[7][8]

XO-2N and XO-2S have a separation of approximately 4,600 AU.[3]

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.[3] 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,[6] and is further supported by a 2024 study.[10]

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.[9] A 2024 study found evidence for a third, super-Jupiter mass planet around XO-2S.[10]

The XO-2N planetary system[6]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
b 0.597±0.021 MJ 0.03673(64) 2.61585922(28) <0.006 87.96+0.42
−0.34° 		1.019±0.031 RJ
The XO-2S planetary system[10]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
b ≥0.26±0.01 MJ 0.1347±0.0025 18.220±0.001 0.15±0.02 — —
c ≥1.38±0.05 MJ 0.4737+0.0085
−0.0088 		120.059±0.013 0.149±0.006 — —
d ≥3.71+1.2
−0.51 MJ 		5.46+0.85
−0.40 		4,696+1,133
−489 		0.091+0.028
−0.018 		— —

See also

References

  1. ^ Roman, Nancy G. (1987). "Identification of a Constellation From a Position". Publications of the Astronomical Society of the Pacific. 99 (617): 695–699. Bibcode:1987PASP...99..695R. doi:10.1086/132034. Vizier query form
  2. ^ a b c d e Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  3. ^ a b c d e Burke, Christopher J.; et al. (2007). "XO-2b: Transiting Hot Jupiter in a Metal-rich Common Proper Motion Binary". The Astrophysical Journal. 671 (2): 2115–2128. arXiv:0705.0003. Bibcode:2007ApJ...671.2115B. doi:10.1086/523087. S2CID 13468914.
  4. ^ a b c d e Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  5. ^ a b Benavides, Rafael; Francisco Rica; Esteban Reina; Julio Castellanos; Ramón Naves; Luis Lahuerta; Salvador Lahuerta (2010). "New Wide Common Proper Motion Binaries". Journal of Double Star Observations. 6 (1): 30. Bibcode:2010JDSO....6...30B.
  6. ^ a b c Damasso, M.; et al. (2015). "The GAPS programme with HARPS-N at TNG. V. A comprehensive analysis of the XO-2 stellar and planetary systems". Astronomy & Astrophysics. 575 A111. arXiv:1501.01424. Bibcode:2015A&A...575A.111D. doi:10.1051/0004-6361/201425332.
  7. ^ a b "TYC 3413-210-1". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-01-28.
  8. ^ a b "TYC 3413-5-1". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-01-28.
  9. ^ a b Desidera, S.; et al. (2014). "The GAPS programme with HARPS-N at TNG. IV. A planetary system around XO-2S". Astronomy and Astrophysics. 567 (6) L6. arXiv:1407.0251. Bibcode:2014A&A...567L...6D. doi:10.1051/0004-6361/201424339. S2CID 118567085.
  10. ^ a b c Ruggieri, A.; Desidera, S.; et al. (April 2024). "The GAPS Programme at TNG. LIII. New insights on the peculiar XO-2 system". Astronomy & Astrophysics. 684: A116. arXiv:2401.17876. Bibcode:2024A&A...684A.116R. doi:10.1051/0004-6361/202348042.

Further reading

  • Fernandez, Jose M.; et al. (2009). "The Transit Light Curve Project. XII. Six Transits of the Exoplanet XO-2b". The Astronomical Journal. 137 (6): 4911–4916. arXiv:0903.2687. Bibcode:2009AJ....137.4911F. doi:10.1088/0004-6256/137/6/4911. S2CID 7113991.
  • Narita, Norio; et al. (2011). "XO-2b: a Prograde Planet with a Negligible Eccentricity and an Additional Radial Velocity Variation". Publications of the Astronomical Society of Japan. 63 (6): L67–L71. arXiv:1110.6136. Bibcode:2011PASJ...63L..67N. doi:10.1093/pasj/63.6.l67. S2CID 119269227.
  • Sing, D. K.; et al. (2011). "Gran Telescopio Canarias OSIRIS transiting exoplanet atmospheric survey: detection of potassium in XO-2b from narrowband spectrophotometry". Astronomy and Astrophysics. 527 A73. arXiv:1008.4795. Bibcode:2011A&A...527A..73S. doi:10.1051/0004-6361/201015579. S2CID 56545385.

External links

  • NASA PlanetQuest: Planet race heats up: 1 month, 32 discoveries
  • "XO-2". Exoplanets. Archived from the original on 2016-03-03. Retrieved 2009-04-28.


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