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Gliese 876 is a red dwarf approximately 15 light-years away from Earth in the constellation of Aquarius. It is one of the closest known stars to the Sun confirmed to possess a planetary system with more than two planets, after Gliese 1061, YZ Ceti, Tau Ceti, and Luyten's Star; as of 2018, four extrasolar planets have been found to orbit the star. The planetary system is also notable for the orbital properties of its planets. It is the only known system of orbital companions to exhibit a near-triple conjunction in the rare phenomenon of Laplace resonance. It is also the first extrasolar system around a normal star with measured coplanarity. While planets b and c are located in the system's habitable zone, they are giant planets believed to be analogous to Jupiter.
HD 82943 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, and it is thought that the system had more giant planets that were "swallowed" by the parent star. HD 82943 is estimated at 1.15 times the mass of the Sun.
HD 169830 is a star in the southern constellation of Sagittarius. It has a yellow-white hue and is dimly visible to the naked eye with an apparent visual magnitude of +5.90. The star is located at a distance of 120 light years from the Sun based on parallax. It is drifting closer with a radial velocity of −17.3 km/s, and is predicted to come as close as 20.7 ly (6.4 pc) in 2.08 million years. HD 169830 is known to be orbited by two large Jupiter-like exoplanets.
HD 4208 is a star in the southern constellation of Sculptor. It has a yellow hue with an apparent visual magnitude of 7.78, making it too dim to be visible to the naked eye. But with binoculars or small telescope it should be an easy target. This object is located at a distance of 111.6 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +57 km/s.
HD 65216 is a triple star system with two exoplanetary companions in the southern constellation of Carina. With an apparent visual magnitude of 7.97 it cannot be readily seen without technical aid, but with binoculars or telescope it should be visible. The system is located at a distance of 114.7 light-years from the Sun based on parallax measurements, and is drifting further away with a radial velocity of 42.6 km/s.
HD 108874 is a yellow dwarf star in the constellation of Coma Berenices. It is 195 light years from Earth and has two extrasolar planets that are possibly in a 9:2 orbital resonance.
HD 1237 is a binary star system approximately 57 light-years away in the constellation of Hydrus.
HD 20782 is a 7th magnitude G-type main sequence star 117.5 light-years away from Earth, in the constellation of Fornax. HD 20782 is a part of a wide binary system in which the other star is designated HD 20781, and both stars host planetary systems. Indeed, this is the first known case of a binary star system where there are planetary systems around both the primary and the secondary stars in the system. The companion star HD 20781 has a very large angular separation of 252 arcsec, corresponding to 9080 AU at the distance of HD 20782. It is estimated to be 7.1 billion years old, with a mass close to that of the Sun.
HD 17156, named Nushagak by the IAU, is a yellow subgiant star approximately 255 light-years away in the constellation of Cassiopeia. The apparent magnitude is 8.17, which means it is not visible to the naked eye but can be seen with good binoculars. A search for a binary companion star using adaptive optics at the MMT Observatory was negative.
Gliese 86 is a K-type main-sequence star approximately 35 light-years away in the constellation of Eridanus. It has been confirmed that a white dwarf orbits the primary star. In 1998 the European Southern Observatory announced that an extrasolar planet was orbiting the star.
HD 40307 is an orange (K-type) main-sequence star located approximately 42 light-years away in the constellation of Pictor, taking its primary name from its Henry Draper Catalogue designation. It is calculated to be slightly less massive than the Sun. The star has six known planets, three discovered in 2008 and three more in 2012. One of them, HD 40307 g, is a potential super-Earth in the habitable zone, with an orbital period of about 200 days. This object might be capable of supporting liquid water on its surface, although much more information must be acquired before its habitability can be assessed.
HD 40307 d is an extrasolar planet orbiting the star HD 40307, located 42 light-years from Earth in the direction of the southern constellation Pictor. The planet was discovered by the radial velocity method, using the HARPS apparatus in June 2008. It is the most massive of the six proposed planets in the system. The planet is of interest as this star has relatively low metallicity, supporting a hypothesis that different metallicities in protostars determine what kind of planets they will form.
HD 47186 is a star located approximately 129 light-years away in the constellation of Canis Major. It is a G6V star with the characteristics very similar to the Sun, but it is 1.7 times more metal-rich. In 2008, two extrasolar planets were discovered orbiting the star.
HD 60532 is a white (F-type) main sequence star located approximately 84 light-years away in the constellation of Puppis, taking its primary name from its Henry Draper Catalogue designation. It is calculated to be 1.44 times more massive than the Sun. The star is only 59% as old as the Sun and has metallicity of only 38% that of the Sun. In 2008, two extrasolar planets were discovered in orbit around it.
HD 60532 b is an extrasolar planet located approximately 84 light-years away in the constellation of Puppis, orbiting the star HD 60532. This planet has a true mass of 3.15 times more than Jupiter, orbits at 0.77 AU, and takes 201.83 days to revolve in an eccentric orbit. This planet was discovered on September 22, 2008 in La Silla Observatory using the HARPS spectrograph. On this same day, the second planet in this system, HD 60532 c, was discovered in a 1:3 orbital resonance.
HD 45364 is a star in the southern constellation of Canis Major. It is too faint to be visible to the naked eye, having an apparent visual magnitude of 8.08. The distance to this system is 112 light years based on parallax. It is drifting further away from the Sun with a radial velocity of +16.4 km/s, having come within 49 light-years some 1.5 million years ago.
HD 204313 is a star with two and possibly three exoplanetary companions in the southern constellation of Capricornus. With an apparent magnitude of 7.99, it is an eighth magnitude star that is too faint to be readily visible to the naked eye. The star is located at a distance of 157 light years from the Sun based on parallax measurements, but it is drifting closer with a radial velocity of −10 km/s.
HD 134606 is a yellow-hued star with a planetary system, positioned in the southern constellation of Apus. It is below the nominal limit for visibility with the naked eye, having an apparent visual magnitude of 6.86. Based upon an annual parallax shift of 37.3 mas, it is located 87.45 light years away. The star appears to be moving further from the Earth with a heliocentric radial velocity of +2.3 km/s.
HD 121056, also known as HIP 67851, is a K-type giant star 209 light-years away in the constellation of Centaurus. Its surface temperature is 4867±49 K. HD 121056’s concentration of heavy elements is similar to the Sun, with a metallicity Fe/H index of 0.020±0.031, although the star is enriched in lighter rock-forming elements like magnesium and aluminum.
References
- Desort, M.; Lagrange, A. -M.; Galland, F.; Beust, H.; Udry, S.; Mayor, M.; Lo Curto, G. (2008). "Extrasolar planets and brown dwarfs around A-F type stars V. A planetary system found with HARPS around the F6IV-V star HD 60532". Astronomy and Astrophysics (abstract). 491 (3): 883–888. arXiv: 0809.3862 . Bibcode:2008yCat..34910883D. doi:10.1051/0004-6361:200810241. S2CID 14562319.
- Laskar, J.; Correia, A. C. M. (2009). "HD60532, a planetary system in a 3:1 mean motion resonance". Astronomy & Astrophysics. 496 (2): L5. arXiv: 0902.0667 . Bibcode:2009A&A...496L...5L. doi:10.1051/0004-6361/200911689. S2CID 17793870.
