HD 82943

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HD 82943

Observation data Epoch 2000
Constellation (pronunciation)	Hydra
Right ascension	09h 34m 50.736s
Declination	−12° 07' 46.365"
Apparent magnitude (V)	6.54
Distance	89.56 ly (27.46 pc)
Spectral type	G0V
Other designations
BD-11°2670, HIP 47007

HD 82943 is a yellow dwarf star (spectral type G0) in the constellation of Hydra, 89.5 light years from our solar system. It is known to be orbited by at least two large extrasolar planets which are locked in a 2:1 orbital resonance.

Contents 1 Planets 1.1 HD 82943 c 1.2 HD 82943 b 2 References 3 External links

[edit] Planets

[edit] HD 82943 c

HD 82943 c

Orbital elements
Semi-major axis a:	0.75 AU
Eccentricity e:	0.38± 0.01
Orbital period P:	219.4 ± 0.2 d
Inclination i:	?°
Angular distance θ:	27.167 mas
Longitude of periastron ω:	124 ± 3°
Time of periastron τ:	2,452,284 ± 1 JD
Semi-amplitude K:	41.7 ± 0.91 m/s
Physical characteristics
Mass:	>1.85 MJ
Radius:	? RJ
Density:	? kg/m³
Gravity:	? g
Temperature:	? K
Discovery
Discovery date:	2001
Discovery site:
Detection method(s):
Discoverer(s):	Mayor, Udry et al.
Other catalogue

HD 82943 c is a gas giant planet almost identical to HD 82943 b in mass. It has an eccentric orbit that sometimes places it very close to the star, and sometimes within its habitable zone.

[edit] HD 82943 b

HD 82943 b

Orbital elements
Semi-major axis a:	1.18 AU
Eccentricity e:	0.18± 0.04
Orbital period P:	435.1 ± 1.4 d
Inclination i:	?°
Angular distance θ:	43.336 mas
Longitude of periastron ω:	237 ± 13°
Time of periastron τ:	2,451,758 ± 13 JD
Semi-amplitude K:	59.3 ± 5.2 m/s
Physical characteristics
Mass:	>1.84 MJ
Radius:	? RJ
Density:	? kg/m³
Gravity:	? g
Temperature:	? K
Discovery
Discovery date:	2000
Discovery site:
Detection method(s):
Discoverer(s):	Mayor, Udry et al.
Other catalogue

HD 82943 b is a gas giant one and a half times the mass of Jupiter. Its orbit is entirely within the star's habitable zone. This means that it might have large moons with atmospheres capable of harboring life.

[edit] References

• Mayor et al. (2004). "The CORALIE survey for southern extra-solar planets XII. Orbital solutions for 16 extra-solar planets discovered with CORALIE" (abstract). Astronomy and Astrophysics 415: 391 – 402. doi:10.1051/0004-6361:20034250. 
• Butler, R. et al. (2006). "Catalog of Nearby Exoplanets". The Astrophysical Journal 646: 505 – 522. doi:10.1086/504701.  (web Preprint)
• Lee et al. (2006). "On the 2:1 Orbital Resonance in the HD 82943 Planetary System". The Astrophysical Journal 641: 1178 – 1187. doi:10.1086/500566.  (web Preprint)

[edit] External links

• http://www.extrasolar.net/planettour.asp?StarCatId=&PlanetId=168
• http://www.extrasolar.net/planettour.asp?StarCatId=&PlanetId=131