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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.
Mu Arae c, also known as HD 160691 c, formally named Dulcinea, is an extrasolar planet orbiting the star Mu Arae of the constellation Ara. It was the first 'hot Neptune' or 'mega-Earth' to be discovered.
HD 40307 c is an extrasolar planet orbiting the star HD 40307, located 42 light-years away in the direction of the southern constellation Pictor. The planet was discovered by the radial velocity method, using the HARPS apparatus, in June 2008. Of the six proposed planets in the HD 40307 star system, it is the third-largest, and has the second-closest orbit from the star. 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 181433 b is an extrasolar planet located approximately 87 light years away in the constellation of Pavo, orbiting the star HD 181433. This planet has mass at least 7.56 times that of Earth. This planet is classified as a super-Earth and orbits at 0.080 AU and varies only about 0.063 AU with an eccentricity of 0.396. François Bouchy et al. have published a paper detailing the HD 181433 planetary system in Astronomy and Astrophysics.
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 181433 d is an extrasolar planet located approximately 87 light years away in the constellation of Pavo, orbiting the star HD 181433. This planet has a minimum mass of 0.54 Jupiter mass and takes 2172 days to orbit the star. The average orbital distance is 3.00 AU. At periastron distance, it will have distance from the star similar to Mars’ distance from the Sun at 1.56 AU. At apastron, the distance is 4.44 AU. These corresponds to the orbital eccentricity of 0.48.
HD 8535 b is an extrasolar planet which orbits the G-type main sequence star HD 8535, located approximately 171 light years away in the constellation Phoenix. This planet has at least five-eighths the mass of Jupiter and takes 3.6 years to orbit the star at a semimajor axis of 2.47 AU. However unlike most other known exoplanets, its eccentricity is not known, but it is typical that its inclination is not known. This planet was detected by HARPS on October 19, 2009, together with 29 other planets.
HD 28254 b is an extrasolar planet which orbits the G-type main sequence star HD 28254, located approximately 178 light years away in the constellation Dorado.
HD 290327 b is an extrasolar planet which orbits the G-type subgiant star HD 290327, located approximately 180 light years away in the constellation Orion. This planet has at least five halves the mass of Jupiter and takes 6.7 years to orbit the star at a semimajor axis of 3.35 AU. However unlike most other known exoplanets, its eccentricity is not known, but it is typical that its inclination is not known. This planet was detected by HARPS on October 19, 2009, together with 29 other planets.
HD 43197 b is an extrasolar planet which orbits the G-type main sequence or subgiant star HD 43197, located approximately 204 light years away in the constellation Canis Major. This planet has a minimum mass 55% that of Jupiter and takes 0.85 years to orbit the star at a semimajor axis of 0.882 AU. Its has a high eccentricity of 0.74, but its inclination is not known. This planet was detected by HARPS on October 19, 2009, together with 29 other planets.
HD 44219 b is an extrasolar planet which orbits the G-type main sequence star HD 44219, located approximately 164 light years away in the constellation Monoceros. This planet has at least three-fifths the mass of Jupiter and takes 1.29 years to orbit the star at a semimajor axis of 1.18 AU. However unlike most other known exoplanets, its eccentricity is not known, but it is typical that its inclination is not known. This planet was detected by HARPS on October 19, 2009, together with 29 other planets.
HD 148156 b is an extrasolar planet which orbits the G-type main sequence star HD 148156, located approximately 168 light years away in the constellation Norma. This planet has at least nine-tenths the mass of Jupiter and takes 25 ninths years to orbit the star at a semimajor axis of 2.06 AU. However unlike most other known exoplanets, its eccentricity is not known, but it is typical that its inclination is not known. This planet was detected by HARPS on October 19, 2009, together with 29 other planets.
HD 156411 b is an extrasolar planet which orbits the G-type main sequence star HD 156411, located approximately 179 light years away in the constellation Ara. This planet has at least three-fourths the mass of Jupiter and takes eight-thirds years to orbit the star at a semimajor axis of 1.81 AU. However unlike most other known exoplanets, its eccentricity is not known, but it is typical that its inclination is not known. This planet was detected by HARPS on October 19, 2009, together with 29 other planets.
HD 154088 is a seventh magnitude metal-rich K-type main sequence star that lies approximately 58 light-years away in the constellation of Ophiuchus. The star is orbited by a hot Super-Earth.
HD 20781 d is an extrasolar planet orbiting the K-type main-sequence star HD 20781 117 light years away in the southern constellation Fornax. It was discovered in 2011 during a survey for southern exoplanets conducted with HARPS using doppler spectroscopy, the radial velocity variations caused by the gravitational pull of the planet. Its existence was confirmed in another survey during 2017.
HD 20003 is a star in the southern constellation Hydrus. With an apparent visual magnitude of 8.39, this yellow-hued star is much too faint to be visible to the naked eye. It is located at a distance of 136.6 light years from the Sun based on parallax. HD 20003 is drifting closer with a radial velocity of −16 km/s, and is predicted to come to within 97 light-years in around 1.4 million years from now.
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.
BD-11 4672 is a 9th magnitude orange dwarf star located 88.7 light-years away in the constellation of Scutum. This star was recognised as a high proper motion star by Max Wolf in 1924. It is a single star, and is the host to two known extrasolar planets.
HD 21693 is a star in the constellation Reticulum. It has an apparent visual magnitude of 7.94, therefore it is not visible to the naked eye. From its parallax measured by the Gaia spacecraft, it is located at a distance of 108.6 light-years (33.3 parsecs) from Earth.
References
- 1 2 Mayor, M.; Marmier, M.; Lovis, C.; Udry, S.; Ségransan, D.; Pepe, F.; Benz, W.; Bertaux, J.-L.; Bouchy, F.; Dumusque, X.; Curto, G. Lo; Mordasini, C.; Queloz, D.; Santos, N. C. (2011). "The HARPS search for southern extra-solar planets XXXIV. Occurrence, mass distribution and orbital properties of super-Earths and Neptune-mass planets". arXiv: 1109.2497 [astro-ph.EP].
- 1 2 3 "Exoplanet Catalog HD 20781". NASA. Retrieved 4 April 2021.
- ↑ "Planet HD 20781 e". The Extrasolar Planet Encyclopaedia. Retrieved 2 January 2016.
- 1 2 3 4 5 Udry, S.; Dumusque, X.; Lovis, C.; Ségransan, D.; Diaz, R. F.; Benz, W.; Bouchy, F.; Coffinet, A.; Lo Curto, G.; Mayor, M.; Mordasini, C.; Motalebi, F.; Pepe, F.; Queloz, D.; Santos, N. C.; Wyttenbach, A.; Alonso, R.; Collier Cameron, A.; Deleuil, M.; Figueira, P.; Gillon, M.; Moutou, C.; Pollacco, D.; Pompei, E. (February 2019). "The HARPS search for southern extra-solar planets: XLIV. Eight HARPS multi-planet systems hosting 20 super-Earth and Neptune-mass companions". Astronomy & Astrophysics. 622: A37. arXiv: 1705.05153 . Bibcode:2019A&A...622A..37U. doi: 10.1051/0004-6361/201731173 . ISSN 0004-6361.
