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16 Cygni or 16 Cyg is the Flamsteed designation of a triple star system approximately 69 light-years away from Earth in the constellation of Cygnus. It consists of two Sun-like yellow dwarf stars, 16 Cygni A and 16 Cygni B, together with a red dwarf, 16 Cygni C. In 1996 an extrasolar planet was discovered in an eccentric orbit around 16 Cygni B.
54 Piscium is an orange dwarf star approximately 36 light-years away in the constellation of Pisces. In 2003, an extrasolar planet was confirmed to be orbiting the star, and in 2006, a brown dwarf was also discovered orbiting it.
16 Cygni Bb or HD 186427 b is an extrasolar planet approximately 69 light-years away in the constellation of Cygnus. The planet was discovered orbiting the Sun-like star 16 Cygni B, one of two solar-mass (M☉) components of the triple star system 16 Cygni in 1996. It orbits its star once every 799 days and was the first eccentric Jupiter and planet in a double star system to be discovered. The planet is abundant in lithium.
HD 4113 is a dual star system in the southern constellation of Sculptor. It is too faint to be viewed with the naked eye, having an apparent visual magnitude of 7.88. The distance to this star, as estimated by parallax measurements, is 137 light years. It is receding away from the Sun with a radial velocity of +5 km/s.
HD 156846 is a binary star system in the equatorial constellation of Ophiuchus, positioned a degree SSE of Messier 9. It has a yellow hue and is just barely bright enough to be visible to the naked eye with an apparent visual magnitude of 6.5. The system is located at a distance of 156 light years from the Sun based on parallax. It is drifting closer with a radial velocity of −68.5 km/s, and is predicted to come to within 85.0 light-years in about 476,000 years.
HD 66428 b is a long-period jovian exoplanet located approximately 174 light-years away in the constellation of Monoceros. It has a minimum mass of 2.82 MJ and takes 1973 days or 5.402 years to orbit around its solar-type star HD 66428. The average distance is 3.18 AU, about half the distance between Mars and Jupiter. This planet is a so-called eccentric Jupiter with an orbital eccentricity of 0.465. At periastron, the distance is 1.70 AU and at apastron, the distance is 4.66 AU. In 2022, the inclination and true mass of HD 66428 b were measured via astrometry.
HD 222582 b is an extrasolar planet that is 8.37 times the mass of Jupiter orbiting the star HD 222582. The orbital period is 572 days and orbits at a semimajor axis of 1.35 AU in one of the most eccentric orbits of the known planets.
HD 33564 b is an extrasolar planet located approximately 68 light-years away in the constellation of Camelopardalis. This planet orbits around F6V star HD 33564. The planet has an eccentric orbit, ranging in distance from 0.737 AU at periastron to 1.497 AU at apastron.
HD 187123 c is an extrasolar planet located approximately 156 light-years away in the constellation of Cygnus, orbiting the star HD 187123. This planet was published in 2006. The radius of the planet's orbit is 4.80 AU, 113 times more distant from the star than first companion. This takes 10 years to orbit. As it is typical for very long-period planets, the orbit is eccentric, referring to as "eccentric Jupiter". At periastron, the orbital distance is 3.60 AU and at apastron, the distance is 6.00 AU. The planet's mass is nearly 2 times that of Jupiter, but is likely to be smaller in size than the inner planet.
HD 114386 b is an exoplanet orbiting the star HD 114386. The planet orbits the star in a rather eccentric orbit. Mean distance from the star is 1.62 AU, somewhat more than distance between Mars and the Sun. At periastron, the planet comes almost as close as Earth orbits the Sun, and at apoastron, the distance is twice as much.
HD 156846 b is an extrasolar planet located approximately 160 light-years away in the constellation of Ophiuchus, orbiting the star HD 156846. It has one of the most eccentric planetary orbits known. The high eccentricity of this planet's orbit is probably attributable to the presence of a red dwarf companion star. The average distance of the planet from HD 156846 is 0.99 AU, nearly identical to the distance of Earth from the Sun. The distance ranges from 0.15 AU to 1.83 AU with a 360-day period, also very close to the period of the Earth. It is also very massive with at least 10.45 Jupiter masses. The mass is a lower limit because the inclination of the orbit is not known; if its inclination and hence true mass became known, it would probably be found to be a brown dwarf, or even a red dwarf.
HD 114729 b is an extrasolar planet approximately 114 light years away in the constellation of Centaurus. This planet is probably slightly less massive than Jupiter. It is an "eccentric Jupiter" meaning that it does not orbit very near the star like the famous 51 Pegasi b but further out and its orbit is very oval-shaped. The mean distance from the star is 2.11 AU, about twice the Earth's distance from the Sun. At periastron, the planet is only 1.43 AU from the star, and at apoastron, the orbital distance is 2.72 AU.
HD 37605 b is an extrasolar planet that is 2.84 times more massive than Jupiter. It orbits close to the star, taking 54 days to revolve around the parent star HD 37605. Its orbit is highly eccentric, around 74%. Distance from HD 37605 ranges from 0.069 to 0.453 astronomical units.
HD 17156 b, named Mulchatna by the IAU, is an extrasolar planet approximately 255 light-years away in the constellation of Cassiopeia. The planet was discovered orbiting the yellow subgiant star HD 17156 in April 2007. The planet is classified as a relatively cool hot Jupiter planet slightly smaller than Jupiter but slightly larger than Saturn. This highly-eccentric three-week orbit takes it approximately 0.0523 AU of the star at periastron before swinging out to approximately 0.2665 AU at apastron. Its eccentricity is about the same as 16 Cygni Bb, a so-called "eccentric Jupiter". Until 2009, HD 17156 b was the transiting planet with the longest orbital period.
HD 181433 c is an extrasolar planet located approximately 87 light-years away in the constellation of Pavo, orbiting the star HD 181433. This planet is at least 0.64 times as massive as Jupiter and takes 962 days to orbit the star at an orbital distance of 1.76 astronomical units (AU), or 263 gigametres (Gm). The orbit is eccentric, however, and ranges from 1.27 AU (190 Gm) at periastron to 2.25 AU (337 Gm) at apastron. François Bouchy et al. have published a paper detailing the HD 181433 planetary system in Astronomy and Astrophysics.
HD 154672 b is an extrasolar planet located approximately 210 light-years away in the constellation of Ara, orbiting the metal-rich and aged star HD 154672. This planet has a minimum mass five times that of Jupiter and orbits at about 60% the distance between the Earth to the Sun. Its orbit is very elliptical, which causes temperatures on the planet to vary significantly as it proceeds along its orbit. This planet was discovered in Las Campanas Observatory on September 5, 2008 using the radial velocity method. Along with HD 205739 b, the planets were the first to be discovered by the N2K Consortium using the Magellan Telescopes.
HD 20868 b is an extrasolar planet located approximately 156 light-years away in the constellation of Fornax, orbiting the 10th magnitude K-type subgiant star HD 20868. This planet has a minimum mass of 1.99 times more than Jupiter and orbits at a distance of 0.947 AU. This planet takes 380.85 days or 12.5 months to revolve around the star with an eccentricity of 0.75, one of the most eccentric of any known extrasolar planets. At periastron, the distance is 0.237 AU and at apastron, the distance is 1.66 AU.
HD 10180, also designated 2MASS J01375356-6030414, is a Sun-like star in the southern constellation Hydrus that is notable for its large planetary system. Since its discovery, at least six exoplanets have been observed orbiting it, and some studies have proposed up to nine potential planets, which would make it potentially the largest of all known planetary systems, including the Solar System.
HD 106906 b is a directly imaged planetary-mass companion and candidate exoplanet orbiting the star HD 106906, in the constellation Crux at about 336 ± 13 light-years (103 ± 4 pc) from Earth. It is estimated to be about eleven times the mass of Jupiter and is located about 738 AU away from its host star. HD 106906 b is rare in astronomy; while its mass estimate is nominally consistent with identifying it as an exoplanet, it appears at a much wider separation from its parent star than thought possible for in-situ formation from a protoplanetary disk.
HD 240237 b is a super-Jupiter exoplanet orbiting the K-type giant star HD 240237 about 4,900 light-years (1,500 parsecs, or nearly 4.6×1016 km) away from Earth in the constellation Cassiopeia. It orbits outside of the habitable zone of its star at a distance of 1.9 AU. The exoplanet was found by using the radial velocity method, from radial-velocity measurements via observation of Doppler shifts in the spectrum of the planet's parent star. The planet has a mildly eccentric orbit.
References
- ↑ Tamuz, O.; et al. (2008). "The CORALIE survey for southern extra-solar planets XV. Discovery of two eccentric planets orbiting HD 4113 and HD 156846". Astronomy and Astrophysics. 480 (3): L33–L36. arXiv: 0710.5028 . Bibcode:2008A&A...480L..33T. doi:10.1051/0004-6361:20078737. S2CID 11350536.
