HD 82943 (164 G. Hydrae) is a star with a pair of orbiting exoplanets in the equatorial constellation of Hydra. It has an apparent visual magnitude of 6.54,[1] which is near the lower limit of visibility to the naked eye. Based on parallax measurements, the distance to this system is 90.3 light years.[2] It is drifting further away with a heliocentric radial velocity of 8.1 km/s.[5] The star shows a high proper motion, traversing the celestial sphere at an angular rate of 0.194 arcsec yr−1.[10]

HD 82943
Observation data
Epoch J2000      Equinox J2000
Constellation Hydra[1]
Right ascension 09h 34m 50.735s[2]
Declination −12° 07′ 46.37″[2]
Apparent magnitude (V) 6.54[1]
Evolutionary stage main sequence[3]
Spectral type F9 V Fe+0.5[4]
B−V color index 0.623±0.001[1]
Radial velocity (Rv)8.102±0.0003[5] km/s
Proper motion (μ) RA: +1.440 mas/yr[2]
Dec.: −174.330 mas/yr[2]
Parallax (π)36.1158 ± 0.0264 mas[2]
Distance90.31 ± 0.07 ly
(27.69 ± 0.02 pc)
Absolute magnitude (MV)4.35[1]
Mass1.14±0.01[6] M
Radius1.17±0.02[6] R
Luminosity1.54±0.02[6] L
Surface gravity (log g)4.35±0.01[6] cgs
Temperature5,944±18[6] K
Metallicity [Fe/H]0.265±0.008[5] dex
Rotation18.0 d[7]
Rotational velocity (v sin i)1.35±0.5[8] km/s
Age3.1±0.4[6] Gyr
Other designations
164 G. Hya, BD−11 2670, HD 82943, HIP 47007, SAO 155312[9]
Database references

The spectrum of HD 82943 presents as an F-type main-sequence star[3] with a stellar classification of F9 V Fe+0.5.[4] The suffix notation indicates a mild strengthening of iron lines relative to a typical star of its type. Nonetheless, it is considered a metal-rich star,[11] having a higher abundance of many elements with masses greater than helium as compared to the Sun. This star is around 3[6] billion years old and is spinning with a rotation period of 18 days.[7] It is 14% more massive and has a 17% larger radius than the Sun. The star is radiating 154% of the luminosity of the Sun from its photosphere at an effective temperature of 5,944 K.[6]

Planetary system edit

The first exoplanet discovered (designated HD 82943 b) was announced in 2000 by a team of French astronomers led by Michel Mayor.[12] The exoplanet orbits its parent star at a mean distance of 1.19 astronomical units (AU) and taking approximately 441 days to complete the orbit. Nearly a year later, a second exoplanet (designated HD 82943 c) was announced by the same discoverers of the previous planet.[13] This exoplanet orbits closer than the other, at a mean distance of 0.746 AU and taking 219 days to complete its orbit.[14] The two known exoplanet appear to have a 2:1 resonance with one another.[14] Further radial velocity analysis hinted at either long-period stellar activity or presence of a third Jovian exoplanet with an orbital period of 1075 days.[15]

Announced in 2001, HD 82943 was found to contain an unusually high abundance of lithium-6. Upon reaching a sufficient core temperature, young stars quickly burn through their initial allotment of lithium-6, whereas planets should retain their lithium-6.[16] Thus the simplest and most convincing answer to explain this observation is that one or more planets, or at least planetary material, have fallen into the star sometime after it passed through its early evolutionary stage.

A circumstellar debris disk was discovered in 2003, based on an infrared excess detected in the system. The inner edge of this disk orbits at a distance of 67 AU from the host star. The distance to the outer edge is poorly constrained.[3]

The HD 82943 planetary system[14]
(in order from star)
Mass Semimajor axis
Orbital period
Eccentricity Inclination Radius
c 14.39 MJ 0.746 219.3 0.359
b 14.5 MJ 1.19 441.2 0.219
d (unconfirmed) 0.29 MJ 2.145 1078

See also edit

References edit

  1. ^ a b c d e 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.
  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 Kennedy, G. M.; et al. (November 2013). "Star-planet-debris disc alignment in the HD 82943 system: is planetary system coplanarity actually the norm". Monthly Notices of the Royal Astronomical Society. 436 (1): 898–903. arXiv:1309.1466. Bibcode:2013MNRAS.436..898K. doi:10.1093/mnras/stt1657.
  4. ^ a b Gray, R. O.; et al. (July 2006). "Contributions to the Nearby Stars (NStars) Project: spectroscopy of stars earlier than M0 within 40 pc-The Southern Sample". The Astronomical Journal. 132 (1): 161–170. arXiv:astro-ph/0603770. Bibcode:2006AJ....132..161G. doi:10.1086/504637. S2CID 119476992.
  5. ^ a b c Soubiran, C.; et al. (2018). "Gaia Data Release 2. The catalogue of radial velocity standard stars". Astronomy and Astrophysics. 616: A7. arXiv:1804.09370. Bibcode:2018A&A...616A...7S. doi:10.1051/0004-6361/201832795. S2CID 52952408.
  6. ^ a b c d e f g h Bonfanti, A.; et al. (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.
  7. ^ a b Mayor, M.; et al. (2004). "The CORALIE survey for southern extra-solar planets XII. Orbital solutions for 16 extra-solar planets discovered with CORALIE". Astronomy and Astrophysics. 415 (1): 391–402. arXiv:astro-ph/0310316. Bibcode:2004A&A...415..391M. doi:10.1051/0004-6361:20034250. S2CID 5233877.
  8. ^ Butler, R. P.; et al. (2006). "Catalog of Nearby Exoplanets". The Astrophysical Journal. 646 (1): 505–522. arXiv:astro-ph/0607493. Bibcode:2006ApJ...646..505B. doi:10.1086/504701. S2CID 119067572.
  9. ^ "HD 82943". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2024-01-07.
  10. ^ Luyten, W. J. (June 1995). "NLTT Catalogue (Luyten, 1979)". VizieR Online Data Catalog. Bibcode:1995yCat.1098....0L.
  11. ^ Santos, N. C.; et al. (November 2000). "Chemical analysis of 8 recently discovered extra-solar planet host stars". Astronomy and Astrophysics. 363: 228–238. arXiv:astro-ph/0009182. Bibcode:2000A&A...363..228S.
  12. ^ "Exoplanets Galore!" (Press release). Garching, Germany: European Southern Observatory. April 15, 2000. Retrieved December 30, 2012.
  13. ^ "Exoplanets: The Hunt Continues!" (Press release). Garching, Germany: European Southern Observatory. April 4, 2001. Retrieved December 27, 2012.
  14. ^ a b c Lee, Man Hoi; et al. (2006). "On the 2:1 Orbital Resonance in the HD 82943 Planetary System". The Astrophysical Journal. 641 (2): 1178–1187. arXiv:astro-ph/0512551. Bibcode:2006ApJ...641.1178L. doi:10.1086/500566. S2CID 119432579.
  15. ^ Baluev, Roman V.; Beaugé, Cristian (2014). "Possible solution to the riddle of HD 82943 multiplanet system: The three-planet resonance 1:2:5?". Monthly Notices of the Royal Astronomical Society. 439 (1): 673–689. arXiv:1310.7101. Bibcode:2014MNRAS.439..673B. doi:10.1093/mnras/stt2486.
  16. ^ "The Harsh Destiny of a Planet?" (Press release). Garching, Germany: European Southern Observatory. May 9, 2001. Retrieved December 30, 2012.

External links edit