HD 82943

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HD 82943
Observation data
Epoch J2000      Equinox J2000
Constellation Hydra
Right ascension  09h 34m 50.73655s[1]
Declination −12° 07′ 46.3733″[1]
Apparent magnitude (V) 6.54
Spectral type F9 V Fe+0.5[2]
Proper motion (μ) RA: +3.00[1] mas/yr
Dec.: -175.01[1] mas/yr
Parallax (π)36.40 ± 0.47[1] mas
Distance90 ± 1 ly
(27.5 ± 0.4 pc)
Mass1.14 ± 0.08[3] M
Surface gravity (log g)4.35 ± 0.04[3] cgs
Temperature5,929 ± 45[3] K
Metallicity [Fe/H]0.34[3] dex
Rotational velocity (v sin i)1.35 ± 0.5[4] km/s
Age3.0 ± 0.7[3] Gyr
Other designations
164 G. Hya, BD-11 2670, HD 82943, HIP 47007, SAO 155312.
Database references

HD 82943 (164 G. Hydrae) is a yellow dwarf star approximately 89 light-years away in the constellation of Hydra. Two extrasolar planets have been confirmed to be orbiting it,[4][5] and it is thought that the system had more giant planets that were "swallowed" by the parent star.[6] HD 82943 is estimated at roughly 1.15 times the mass of the Sun.[7]

Planetary system[edit]

The first planet discovered (designated HD 82943 b) was announced in 2000 by a team of French astronomers led by Michel Mayor.[8] The planet 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 planet (designated HD 82943 c) was announced by the same discoverers of the previous planet.[9] This planet orbits closer than the other, at a mean distance of 0.746 AU and taking 219 days to complete its orbit.[7] The two known planets appear to have a 2:1 resonance with one another.[7] Further radial velocity analysis hinted at either long-period stellar activity or presence of a third Jovian planet with an orbital period of 1075 days.[10]

Announced in 2001, HD 82943 was found to contain an unusually high amount of lithium-6. Stars do not naturally contain lithium-6, but unlike stars, planets never reach temperatures that are high enough to burn their initial content of lithium-6 (planets should retain lithium-6).[6] 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.

The HD 82943 planetary system[7]
(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 0.29 MJ 2.145 1078 -

See also[edit]


  1. ^ a b c d e van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357
  2. ^ 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
  3. ^ a b c d e Trevisan, M.; et al. (November 2011), "Analysis of old very metal rich stars in the solar neighbourhood", Astronomy & Astrophysics, 535: A42, arXiv:1109.6304, Bibcode:2011A&A...535A..42T, doi:10.1051/0004-6361/201016056. See table 13.
  4. ^ a b 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.
  5. ^ 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.
  6. ^ a b "The Harsh Destiny of a Planet?" (Press release). Garching, Germany: European Southern Observatory. May 9, 2001. Retrieved December 30, 2012.
  7. ^ a b c d 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.
  8. ^ "Exoplanets Galore!" (Press release). Garching, Germany: European Southern Observatory. April 15, 2000. Retrieved December 30, 2012.
  9. ^ "Exoplanets: The Hunt Continues!" (Press release). Garching, Germany: European Southern Observatory. April 4, 2001. Retrieved December 27, 2012.
  10. ^ https://arxiv.org/abs/1310.7101

External links[edit]

Coordinates: Sky map 09h 34m 50.736s, −12° 07′ 46.365″