HD 204313
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Capricornus
Right ascension 21h 28m 12.20609s[1]
Declination −21° 43′ 34.5182″[1]
Apparent magnitude (V) 7.99[2]
Characteristics
Spectral type G5V[3]
Apparent magnitude (B) 8.687[2]
Apparent magnitude (J) 6.812±0.024[2]
Apparent magnitude (H) 6.539±0.040[2]
Apparent magnitude (K) 6.459±0.018[2]
B−V color index 0.697±0.022[2]
Astrometry
Radial velocity (Rv)−9.79±0.12[1] km/s
Proper motion (μ) RA: 42.751 mas/yr[1]
Dec.: −270.443 mas/yr[1]
Parallax (π)20.7705 ± 0.0343 mas[1]
Distance157.0 ± 0.3 ly
(48.15 ± 0.08 pc)
Absolute magnitude (MV)4.61[2]
Details
Mass1.06±0.03[4] M☉
Radius1.08±0.03[4] R☉
Luminosity1.18±0.03[4] L☉
Surface gravity (log g)4.39±0.04[4] cgs
Temperature5,783±48[4] K
Metallicity [Fe/H]0.18[5] dex
Rotational velocity (v sin i)0.846[5] km/s
Age4.3±1.8[4] Gyr
Other designations
CD–22°5691, GC 30045, HD 204313, HIP 106006, SAO 190362, PPM 272526, LTT 8525[6]
Database references
SIMBADdata
Exoplanet Archivedata

HD 204313 is a star with two and possibly three exoplanetary companions in the southern constellation of Capricornus. With an apparent magnitude of 7.99,[2] it is an eighth magnitude star that is too faint to be readily visible to the naked eye. The star is located at a distance of 157 light years from the Sun based on parallax measurements, but it is drifting closer with a radial velocity of −10 km/s.[1]

This is an ordinary G-type main-sequence star with a stellar classification of G5V,[3] which indicates it is generating energy through hydrogen fusion at its core. It is an estimated four billion years old, chromospherically extremely quiet,[7] and is spinning with a projected rotational velocity of just 0.8 km/s.[5] The star has a slightly larger mass and radius compared to the Sun. It is radiating 118% of the luminosity of the Sun from its photosphere at an effective temperature of 5,783 K.[4]

Planetary system

This star was in observation by the CORALIE radial velocity planet-search program since the year 2000. In August 2009, a superjovian planetary companion was announced.[8] Two years later, a hot Neptune HD 204313 c on a 35-day orbit was announced,[9] followed by a third Jupiter-like planet candidate HD 204313 d on a 2800-day orbit, which was announced in 2012.[10] Assuming that planet d exists, planets b & d are apparently orbiting close to a 7:5 mean motion resonance, which may be stabilizing their periods.[11]

A 2015 study independently confirmed the first two discoveries, but did not detect any significant signal at the claimed period of planet d.[12] Another study in 2022 agreed with these results, in addition to finding a new planet or brown dwarf, designated HD 204313 e to differentiate it from the dubious candidate. The inclination and true mass of planets b & e were measured via astrometry.[13]

The HD 204313 planetary system[12][13]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
c ≥17.6±1.7 M🜨 0.2099±0.0071 34.905±0.012 0.059+0.051
−0.041 		— —
b 4.615+1.290
−0.306 MJ 		3.185+0.130
−0.143 		2041.1+1.7
−1.9 		0.100±0.003 72.917+31.372
−21.476° 		—
e 15.317+4.890
−5.183 MJ 		7.457+0.399
−0.427 		7325.6+399.9
−369.1 		0.253+0.071
−0.065 		176.092+0.963
−2.122° 		—

See also

References

  1. ^ a b c d e f 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.
  2. ^ a b c d e f g h Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. S2CID 119257644.
  3. ^ a b Houk, Nancy; Smith-Moore, M. (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, vol. 4, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1988mcts.book.....H
  4. ^ a b c d e f g Bonfanti, A.; Ortolani, S.; Nascimbeni, V. (2016). "Age consistency between exoplanet hosts and field stars". Astronomy & Astrophysics. 585: 14. arXiv:1511.01744. Bibcode:2016A&A...585A...5B. doi:10.1051/0004-6361/201527297. S2CID 53971692. A5.
  5. ^ a b c Costa Silva, A. R.; et al. (February 2020). "Chemical abundances of 1111 FGK stars from the HARPS-GTO planet search sample. III. Sulfur". Astronomy & Astrophysics. 634: 10. arXiv:1912.08659. Bibcode:2020A&A...634A.136C. doi:10.1051/0004-6361/201936523. S2CID 209405391. A136.
  6. ^ "HD 204313". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-10-16.
  7. ^ Robertson, Paul; et al. (July 2012), "A Second Giant Planet in 3:2 Mean-motion Resonance in the HD 204313 System", The Astrophysical Journal, 754 (1): 9, arXiv:1205.3689, Bibcode:2012ApJ...754...50R, doi:10.1088/0004-637X/754/1/50, S2CID 118630310, 50.
  8. ^ Ségransan, D.; et al. (2010). "The CORALIE survey for southern extrasolar planets. XVI. Discovery of a planetary system around HD 147018 and of two long period and massive planets orbiting HD 171238 and HD 204313". Astronomy and Astrophysics. 511: A45. arXiv:0908.1479. Bibcode:2010A&A...511A..45S. doi:10.1051/0004-6361/200912136. S2CID 8864844.
  9. ^ Mayor, M.; et al. (September 2011), "The HARPS search for southern extra-solar planets XXXIV. Occurrence, mass distribution and orbital properties of super-Earths and Neptune-mass planets", eprint, arXiv:1109.2497, Bibcode:2011arXiv1109.2497M
  10. ^ Robertson, Paul; et al. (2012). "A Second Giant Planet in 3:2 Mean-motion Resonance in the HD 204313 System". The Astrophysical Journal. 754 (1): 50. arXiv:1205.3689. Bibcode:2012ApJ...754...50R. doi:10.1088/0004-637X/754/1/50. S2CID 118630310.
  11. ^ Petit, A. C.; et al. (November 2017), "AMD-stability in the presence of first-order mean motion resonances", Astronomy & Astrophysics, 607: 17, arXiv:1705.06756, Bibcode:2017A&A...607A..35P, doi:10.1051/0004-6361/201731196, S2CID 55740532, A35.
  12. ^ a b Díaz, R. F.; et al. (2016). "The HARPS search for southern extra-solar planets. XXXVIII. Bayesian re-analysis of three systems. New super-Earths, unconfirmed signals, and magnetic cycles". Astronomy and Astrophysics. 585. A134. arXiv:1510.06446. Bibcode:2016A&A...585A.134D. doi:10.1051/0004-6361/201526729. S2CID 118531921.
  13. ^ a b Feng, Fabo; Butler, R. Paul; et al. (August 2022). "3D Selection of 167 Substellar Companions to Nearby Stars". The Astrophysical Journal Supplement Series. 262 (21): 21. arXiv:2208.12720. Bibcode:2022ApJS..262...21F. doi:10.3847/1538-4365/ac7e57. S2CID 251864022.


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