XO-2 (star)

XO-2 is a binary star. It consists of two components: XO-2S (Also known as XO-2A) and XO-2N (Also known as XO-2B).[5]

XO-2
Observation data
Epoch 2000      Equinox 2000
Constellation Lynx[1]
XO-2S
Right ascension  07h 48m 07.4814s[2]
Declination +50° 13′ 03.2578″[2]
Apparent magnitude (V) 11.12±0.03[3]
XO-2N
Right ascension  07h 48m 06.4726s[4]
Declination +50° 13′ 32.9211″[4]
Apparent magnitude (V) 11.18±0.03[3]
Characteristics
Spectral type K0V + K0V[3]
Astrometry
XO-2S
Proper motion (μ) RA: −29.317±0.063[2] mas/yr
Dec.: −154.398±0.044[2] mas/yr
Parallax (π)6.5765 ± 0.0411[2] mas
Distance496 ± 3 ly
(152.1 ± 1.0 pc)
XO-2N
Proper motion (μ) RA: −29.731±0.083[4] mas/yr
Dec.: −154.272±0.050[4] mas/yr
Parallax (π)6.4539 ± 0.0603[4] mas
Distance505 ± 5 ly
(155 ± 1 pc)
Details
XO-2S
Mass0.982 ± 0.034[5] M☉
Radius1.02[5] R☉
Temperature5399 ± 55 [5] K
Metallicity [Fe/H]0.39 ± 0.05[5] dex
Age7.1 ± +2.5
−2.9[5] Gyr
XO-2N
Mass0.971 ± 0.034[6] M☉
Radius0.976+0.024
−0.016[6] R☉
Temperature5340 ± 32[3] K
Age6.3 ± 2.4[6] Gyr
Other designations
XO-2S: LSPM J0748+5013S, TYC 3413-210-1, GSC 03413-00210, 2MASS J07480748+5013032[7]
XO-2N: LSPM J0748+5013N, TYC 3413-5-1, GSC 03413-00005, 2MASS J07480647+5013328[8]
Database references
SIMBADXO-2S
XO-2N

This system is located approximately 500 light-years away from Earth in the Lynx constellation. Both of these 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 are two known exoplanets orbiting XO-2N. XO-2Nb (or rarely XO-2Bb), which is classified as a hot Jupiter, was discovered by the XO Telescope using the transit method orbiting XO-2N (XO-2B) in 2007[3] and XO-2Nc was discovered in 2015 using the radial velocity method.[9][10]

Two planets were reported to orbit around XO-2S in 2014 using radial velocity method. One of them is Jupiter-mass and another has a mass comparable to Saturn.[5]

Both stars also show RV-trends, which may indicate the presence of additional long-periodic jovians or brown dwarfs around each of them.

The XO-2S planetary system[5]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b ≥ 0.259 ± 0.014 MJ 0.1344 ±0.0025 18.157 ± 0.034 0.18 ± 0.035 — —
c ≥ 1.37 ± 0.053 MJ 0.4756 ±0.0087 120.8 ± 0.034 0.1528 ± 0.01 — —
The XO-2N planetary system[11][12]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b 0.62 ± 0.02 MJ 0.0369 ±0.002 2.61586178 ± 0.00000075 0.045 ± 0.024 88.7 ± 1.3° 0.973 ± 0.03 RJ
c 1.8 MJ — >6200 — — —
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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. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  3. 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.
  4. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  5. 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.
  6. 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.
  7. "TYC 3413-210-1". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-01-28.
  8. "TYC 3413-5-1". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-01-28.
  9. Damasso, M.; et al. (2015). "A comprehensive analysis of the XO-2 stellar and planetary systems". Astronomy & Astrophysics. 575. A111. doi:10.1051/0004-6361/201425332.
  10. "XO-2c". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-06-09.
  11. 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.
  12. 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.

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