XO-2

Last updated
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]
Distance 489 ± 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]
Distance 490 ± 1  ly
(150.2 ± 0.4  pc)
Absolute magnitude  (MV)5.74 [5]
Details [6]
XO-2S
Mass 0.98±0.05  M☉
Radius 1.02+0.09
−0.06  R☉
Luminosity 0.79±0.14  L☉
Surface gravity (log g)4.420±0.094  cgs
Temperature 5,325±37  K
Metallicity [Fe/H]0.32±0.08  dex
Rotation 26.0±0.6  d
Rotational velocity (v sin i)1.5±0.3 km/s
Age 7.1+2.5
−2.9  Gyr
XO-2N
Mass 0.96±0.05  M☉
Radius 0.998+0.033
−0.032  R☉
Luminosity0.70±0.04  L☉
Surface gravity (log g)4.43±0.10  cgs
Temperature 5,290±18  K
Metallicity [Fe/H]0.37±0.07  dex
Rotation 41.6±1.1  d
Rotational velocity (v sin i)1.07±0.09 km/s
Age 7.8+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
SIMBAD XO-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]

Contents

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)<0.00687.96+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±0.002518.220±0.0010.15±0.02——
c≥1.38±0.05  MJ 0.4737+0.0085
−0.0088		120.059±0.0130.149±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

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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. 1 2 3 4 5 6 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. 1 2 3 4 5 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. 1 2 3 4 5 6 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. 1 2 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. 1 2 3 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. 1 2 "TYC 3413-210-1". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2018-01-28.
  8. 1 2 "TYC 3413-5-1". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2018-01-28.
  9. 1 2 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. 1 2 3 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.

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