# HD 82943

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Star in the constellation Hydra

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] Characteristics Evolutionary stage main sequence[3] Spectral type F9 V Fe+0.5[4] B−V color index 0.623±0.001[1] Astrometry 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] Distance 90.31 ± 0.07 ly (27.69 ± 0.02 pc) Absolute magnitude (MV) 4.35[1] Details Mass 1.14±0.01[6] M☉ Radius 1.17±0.02[6] R☉ Luminosity 1.54±0.02[6] L☉ Surface gravity (log g) 4.35±0.01[6] cgs Temperature 5,944±18[6] K Metallicity [Fe/H] 0.265±0.008[5] dex Rotation 18.0 d[7] Rotational velocity (v sin i) 1.35±0.5[8] km/s Age 3.1±0.4[6] Gyr Other designations 164 G. Hya, BD−11 2670, HD 82943, HIP 47007, SAO 155312[9] Database references SIMBAD data Exoplanet Archive data

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

The [spectrum](/source/Astronomical_spectroscopy) of HD 82943 presents as an [F-type main-sequence star](/source/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](/source/Absorption_line) 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](/source/Rotation_period) of 18 days.[7] It is 14% more [massive](/source/Solar_mass) and has a 17% larger [radius](/source/Solar_radius) than the Sun. The star is radiating 154% of the [luminosity of the Sun](/source/Luminosity_of_the_Sun) from its [photosphere](/source/Photosphere) at an [effective temperature](/source/Effective_temperature) of 5,944 K.[6]

## Planetary system

The first exoplanet discovered (designated [HD 82943 b](/source/HD_82943_b)) was announced in 2000 by a team of French astronomers led by [Michel Mayor](/source/Michel_Mayor).[12] The exoplanet orbits its parent star at a mean distance of 1.19 [astronomical units](/source/Astronomical_unit) (AU) and taking approximately 441 [days](/source/Day) to complete the orbit. Nearly a year later, a second exoplanet (designated [HD 82943 c](/source/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](/source/Orbital_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 1,075 days.[15]

Announced in 2001, HD 82943 was found to contain an unusually high abundance of [lithium-6](/source/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](/source/Debris_disk) was discovered in 2003, based on an [infrared excess](/source/Infrared_excess) detected in the system. The inner edge of this disk orbits at a distance of 67 [AU](/source/Astronomical_unit) from the host star. The distance to the outer edge is poorly constrained.[3]

The HD 82943 planetary system[14] Companion (in order from star) Mass Semimajor axis (AU) Orbital period (days) 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

- [Gliese 876](/source/Gliese_876)

- [HD 169830](/source/HD_169830)

- [Mu Arae](/source/Mu_Arae)

## References

1. ^ [***a***](#cite_ref-Anderson_Francis_2012_1-0) [***b***](#cite_ref-Anderson_Francis_2012_1-1) [***c***](#cite_ref-Anderson_Francis_2012_1-2) [***d***](#cite_ref-Anderson_Francis_2012_1-3) [***e***](#cite_ref-Anderson_Francis_2012_1-4) Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". *Astronomy Letters*. **38** (5): 331. [arXiv](/source/ArXiv_(identifier)):[1108.4971](https://arxiv.org/abs/1108.4971). [Bibcode](/source/Bibcode_(identifier)):[2012AstL...38..331A](https://ui.adsabs.harvard.edu/abs/2012AstL...38..331A). [doi](/source/Doi_(identifier)):[10.1134/S1063773712050015](https://doi.org/10.1134%2FS1063773712050015). [S2CID](/source/S2CID_(identifier)) [119257644](https://api.semanticscholar.org/CorpusID:119257644).

1. ^ [***a***](#cite_ref-GaiaDR3_2-0) [***b***](#cite_ref-GaiaDR3_2-1) [***c***](#cite_ref-GaiaDR3_2-2) [***d***](#cite_ref-GaiaDR3_2-3) [***e***](#cite_ref-GaiaDR3_2-4) Vallenari, A.; et al. (Gaia collaboration) (2023). ["*Gaia* Data Release 3. Summary of the content and survey properties"](https://doi.org/10.1051%2F0004-6361%2F202243940). *Astronomy and Astrophysics*. **674**: A1. [arXiv](/source/ArXiv_(identifier)):[2208.00211](https://arxiv.org/abs/2208.00211). [Bibcode](/source/Bibcode_(identifier)):[2023A&A...674A...1G](https://ui.adsabs.harvard.edu/abs/2023A&A...674A...1G). [doi](/source/Doi_(identifier)):[10.1051/0004-6361/202243940](https://doi.org/10.1051%2F0004-6361%2F202243940). [S2CID](/source/S2CID_(identifier)) [244398875](https://api.semanticscholar.org/CorpusID:244398875). [Gaia DR3 record for this source](https://vizier.cds.unistra.fr/viz-bin/VizieR-4?-source=+I%2F355&-from=nav&-nav=cat%3AI%2F355%26tab%3A%7BI%2F355%2Fgaiadr3%7D%26key%3Asource%3D1355%2Fgaiadr3%26HTTPPRM%3A%26-out.add%3D.%26Source%3D%3D%3D2919760965879179136%26-go+%25%23Sesame%23%25%26) at [VizieR](/source/VizieR).

1. ^ [***a***](#cite_ref-Kennedy_et_al_2013_3-0) [***b***](#cite_ref-Kennedy_et_al_2013_3-1) [***c***](#cite_ref-Kennedy_et_al_2013_3-2) Kennedy, G. M.; et al. (November 2013). ["Star-planet-debris disc alignment in the HD 82943 system: is planetary system coplanarity actually the norm"](https://doi.org/10.1093%2Fmnras%2Fstt1657). *Monthly Notices of the Royal Astronomical Society*. **436** (1): 898–903. [arXiv](/source/ArXiv_(identifier)):[1309.1466](https://arxiv.org/abs/1309.1466). [Bibcode](/source/Bibcode_(identifier)):[2013MNRAS.436..898K](https://ui.adsabs.harvard.edu/abs/2013MNRAS.436..898K). [doi](/source/Doi_(identifier)):[10.1093/mnras/stt1657](https://doi.org/10.1093%2Fmnras%2Fstt1657).

1. ^ [***a***](#cite_ref-aj132_1_161_4-0) [***b***](#cite_ref-aj132_1_161_4-1) 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](/source/The_Astronomical_Journal)*. **132** (1): 161–170. [arXiv](/source/ArXiv_(identifier)):[astro-ph/0603770](https://arxiv.org/abs/astro-ph/0603770). [Bibcode](/source/Bibcode_(identifier)):[2006AJ....132..161G](https://ui.adsabs.harvard.edu/abs/2006AJ....132..161G). [doi](/source/Doi_(identifier)):[10.1086/504637](https://doi.org/10.1086%2F504637). [S2CID](/source/S2CID_(identifier)) [119476992](https://api.semanticscholar.org/CorpusID:119476992).

1. ^ [***a***](#cite_ref-Soubiran_et_al_2018_5-0) [***b***](#cite_ref-Soubiran_et_al_2018_5-1) [***c***](#cite_ref-Soubiran_et_al_2018_5-2) Soubiran, C.; et al. (2018). "Gaia Data Release 2. The catalogue of radial velocity standard stars". *Astronomy and Astrophysics*. **616**: A7. [arXiv](/source/ArXiv_(identifier)):[1804.09370](https://arxiv.org/abs/1804.09370). [Bibcode](/source/Bibcode_(identifier)):[2018A&A...616A...7S](https://ui.adsabs.harvard.edu/abs/2018A&A...616A...7S). [doi](/source/Doi_(identifier)):[10.1051/0004-6361/201832795](https://doi.org/10.1051%2F0004-6361%2F201832795). [S2CID](/source/S2CID_(identifier)) [52952408](https://api.semanticscholar.org/CorpusID:52952408).

1. ^ [***a***](#cite_ref-Bonfanti_et_al_2016_6-0) [***b***](#cite_ref-Bonfanti_et_al_2016_6-1) [***c***](#cite_ref-Bonfanti_et_al_2016_6-2) [***d***](#cite_ref-Bonfanti_et_al_2016_6-3) [***e***](#cite_ref-Bonfanti_et_al_2016_6-4) [***f***](#cite_ref-Bonfanti_et_al_2016_6-5) [***g***](#cite_ref-Bonfanti_et_al_2016_6-6) [***h***](#cite_ref-Bonfanti_et_al_2016_6-7) Bonfanti, A.; et al. (2016). "Age consistency between exoplanet hosts and field stars". *Astronomy & Astrophysics*. **585**: 14. [arXiv](/source/ArXiv_(identifier)):[1511.01744](https://arxiv.org/abs/1511.01744). [Bibcode](/source/Bibcode_(identifier)):[2016A&A...585A...5B](https://ui.adsabs.harvard.edu/abs/2016A&A...585A...5B). [doi](/source/Doi_(identifier)):[10.1051/0004-6361/201527297](https://doi.org/10.1051%2F0004-6361%2F201527297). [S2CID](/source/S2CID_(identifier)) [53971692](https://api.semanticscholar.org/CorpusID:53971692). A5.

1. ^ [***a***](#cite_ref-Mayor2004_7-0) [***b***](#cite_ref-Mayor2004_7-1) 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](/source/ArXiv_(identifier)):[astro-ph/0310316](https://arxiv.org/abs/astro-ph/0310316). [Bibcode](/source/Bibcode_(identifier)):[2004A&A...415..391M](https://ui.adsabs.harvard.edu/abs/2004A&A...415..391M). [doi](/source/Doi_(identifier)):[10.1051/0004-6361:20034250](https://doi.org/10.1051%2F0004-6361%3A20034250). [S2CID](/source/S2CID_(identifier)) [5233877](https://api.semanticscholar.org/CorpusID:5233877).

1. **[^](#cite_ref-Butler2006_8-0)** Butler, R. P.; et al. (2006). "Catalog of Nearby Exoplanets". *The Astrophysical Journal*. **646** (1): 505–522. [arXiv](/source/ArXiv_(identifier)):[astro-ph/0607493](https://arxiv.org/abs/astro-ph/0607493). [Bibcode](/source/Bibcode_(identifier)):[2006ApJ...646..505B](https://ui.adsabs.harvard.edu/abs/2006ApJ...646..505B). [doi](/source/Doi_(identifier)):[10.1086/504701](https://doi.org/10.1086%2F504701). [S2CID](/source/S2CID_(identifier)) [119067572](https://api.semanticscholar.org/CorpusID:119067572).

1. **[^](#cite_ref-SIMBAD_9-0)** ["HD 82943"](http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+82943). *[SIMBAD](/source/SIMBAD)*. [Centre de données astronomiques de Strasbourg](/source/Centre_de_donn%C3%A9es_astronomiques_de_Strasbourg). Retrieved 2024-01-07.

1. **[^](#cite_ref-Luyten1995_10-0)** Luyten, W. J. (June 1995). "NLTT Catalogue (Luyten, 1979)". *VizieR Online Data Catalog*. [Bibcode](/source/Bibcode_(identifier)):[1995yCat.1098....0L](https://ui.adsabs.harvard.edu/abs/1995yCat.1098....0L).

1. **[^](#cite_ref-Santos_et_al_2000_11-0)** 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](/source/ArXiv_(identifier)):[astro-ph/0009182](https://arxiv.org/abs/astro-ph/0009182). [Bibcode](/source/Bibcode_(identifier)):[2000A&A...363..228S](https://ui.adsabs.harvard.edu/abs/2000A&A...363..228S).

1. **[^](#cite_ref-eso0019_12-0)** ["Exoplanets Galore!"](http://www.eso.org/public/news/eso0019/) (Press release). Garching, Germany: [European Southern Observatory](/source/European_Southern_Observatory). April 15, 2000. Retrieved December 30, 2012.

1. **[^](#cite_ref-eso0114_13-0)** ["Exoplanets: The Hunt Continues!"](https://www.eso.org/public/news/eso0114/) (Press release). Garching, Germany: European Southern Observatory. April 4, 2001. Retrieved May 3, 2026.

1. ^ [***a***](#cite_ref-Lee2006_14-0) [***b***](#cite_ref-Lee2006_14-1) [***c***](#cite_ref-Lee2006_14-2) 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](/source/ArXiv_(identifier)):[astro-ph/0512551](https://arxiv.org/abs/astro-ph/0512551). [Bibcode](/source/Bibcode_(identifier)):[2006ApJ...641.1178L](https://ui.adsabs.harvard.edu/abs/2006ApJ...641.1178L). [doi](/source/Doi_(identifier)):[10.1086/500566](https://doi.org/10.1086%2F500566). [S2CID](/source/S2CID_(identifier)) [119432579](https://api.semanticscholar.org/CorpusID:119432579).

1. **[^](#cite_ref-Baluev_Beaugé_2014_15-0)** Baluev, Roman V.; Beaugé, Cristian (2014). ["Possible solution to the riddle of HD 82943 multiplanet system: The three-planet resonance 1:2:5?"](https://doi.org/10.1093%2Fmnras%2Fstt2486). *Monthly Notices of the Royal Astronomical Society*. **439** (1): 673–689. [arXiv](/source/ArXiv_(identifier)):[1310.7101](https://arxiv.org/abs/1310.7101). [Bibcode](/source/Bibcode_(identifier)):[2014MNRAS.439..673B](https://ui.adsabs.harvard.edu/abs/2014MNRAS.439..673B). [doi](/source/Doi_(identifier)):[10.1093/mnras/stt2486](https://doi.org/10.1093%2Fmnras%2Fstt2486).

1. **[^](#cite_ref-eso0118_16-0)** ["The Harsh Destiny of a Planet?"](http://www.eso.org/public/news/eso0118/) (Press release). Garching, Germany: [European Southern Observatory](/source/European_Southern_Observatory). May 9, 2001. Retrieved December 30, 2012.

## External links

- Nemiroff, R.; Bonnell, J., eds. (18 May 2001). ["HD 82943: Planet Swallower"](https://apod.nasa.gov/apod/ap010518.html). *[Astronomy Picture of the Day](/source/Astronomy_Picture_of_the_Day)*. [NASA](/source/NASA). Retrieved 2008-07-15.

- ["Notes for star HD 82943"](https://web.archive.org/web/20071106060202/http://exoplanet.eu/star.php?st=HD+82943). *[Extrasolar Planets Encyclopaedia](/source/Extrasolar_Planets_Encyclopaedia)*. Archived from [the original](http://exoplanet.eu/star.php?st=HD+82943) on November 6, 2007. Retrieved 2008-07-15.

- ["The Harsh Destiny of a Planet?"](https://web.archive.org/web/20080507074309/http://www.eso.org/public/outreach/press-rel/pr-2001/pr-10-01.html). *[European Southern Observatory](/source/European_Southern_Observatory)*. 2001-05-09. Archived from [the original](http://www.eso.org/public/outreach/press-rel/pr-2001/pr-10-01.html) on 2008-05-07. Retrieved 2008-07-15.

- [Extrasolar Planet Interactions](http://www.lpl.arizona.edu/~rory/research/xsp/dynamics/) [Archived](https://web.archive.org/web/20160505160348/http://www.lpl.arizona.edu/~rory/research/xsp/dynamics/) 2016-05-05 at the [Wayback Machine](/source/Wayback_Machine) by Rory Barnes & Richard Greenberg, Lunar and Planetary Lab, University of Arizona

v t e Constellation of Hydra List of stars in Hydra Hydra in Chinese astronomy Stars Bayer α (Alphard) β γ (Naga) δ ε (Ashlesha) ζ η θ ι (Ukdah) κ λ μ ν ξ ο π ρ σ (Minchir) τ1 τ2 υ1 (Zhang) υ2 φ1 φ2 φ3 χ1 χ2 ψ ω b1 b3 C F Flamsteed 1 2 3 6 (a) 9 10 12 (D) 14 15 17 19 20 21 23 24 25 26 27 (P) 28 29 33 (A) 34 37 44 47 48 50 51 (k) 52 (l) 54 (m) 55 56 57 58 (Solitaire) 59 60 10 Crt 17 Crt 20 Crt 2 Sex Variable R U V W TW EX HS KU LQ V361 V419 V421 V478 V484 HR 3378 3538 3749 (G) 3750 3858 (I) 3862 3919 3923 (Felis) 4162 4328 4339 (β Ant) 4445 5265 HD 72659 74156 82943 86226 86264 90156 (γ Ant) Other 2MASS 1114−2618 ESO 439-26 Gliese 328 Gliese 357 Gliese 433 Gliese 453 GJ 3634 HAT-P-30 HE 1256−2738 HE 1327−2326 LHS 2065 LHS 3003 LTT 3780 SDSS J090745.0+024507 WASP-25 WASP-36 WASP-84 WASP-166 (Filetdor) WISE 0855−0714 WISEA J1141−3326 Exoplanets Gliese 357 d HD 72659 b HD 74156 b c HD 82943 b c HD 86226 b HD 86264 b TW Hydrae b (unconfirmed) WASP-193b Star clusters Messier 48 Messier 68 NGC 5694 Price-Whelan 1 Nebulae Abell 33 Abell 35 NGC 3242 Southern Owl Nebula Galaxies Messier 83 NGC 2617 2642 2697 2708 2758 2835 2848 2865 2890 2935 2936 2937 2960 2962 2986 2992 3030 3052 3054 3081 3109 3124 3200 3285 3285B 3290 3305 3307 3308 3309 3311 3312 3313 3314 3315 3316 3336 3369 3383 3393 3402 3463 3464 3585 3621 3673 3717 3904 3923 3936 4980 4993 5042 5061 5078 5085 5101 5135 5260 5264 5495 5626 Other 3C 196.1 AM 1316−241 Arp 7 CTQ 327 ESO 510-G13 GAMA202627 GLEAM J0917−0012 Hydra A IC 535 MRC 1138−262 Peekaboo Galaxy PKS 1151−348 RX J0911.4+0551 SDSS J0841+0101 TN J0924−2201 Tololo 1247−232 ZwCl 1693 BCG Galaxy clusters Abell 754 Abell 3411 Abell 3412 Bullet Group Hickson 40 Astronomical events GW170817 Category

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