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HD 2638 is a ternary star system system in the equatorial constellation of Cetus. The pair have an angular separation of 0.53″ along a position angle of 166.7°, as of 2015. This is system too faint to be visible to the naked eye, having a combined apparent visual magnitude of 9.44; a small telescope is required. The distance to this system is 179.5 light years based on parallax, and it is drifting further away with a radial velocity of +9.6 km/s. The magnitude 7.76 star HD 2567 forms a common proper motion companion to this pair at projected separation 839″.
HD 27894 is a 9th magnitude star located approximately 143 light years away in the constellation of Reticulum. It is an orange dwarf, a type dimmer and cooler than the Sun.
HD 102195 is an orange-hued star in the zodiac constellation of Virgo with a confirmed exoplanet companion. With an apparent visual magnitude of 8.07, the star is too faint to be seen with the naked eye. The distance to HD 102195 can be estimated from its annual parallax shift of 34.06 mas, yielding a separation of 95.8 light years. It is moving further away from the Earth with a heliocentric radial velocity of 1.85 km/s. This is a high proper motion star and a possible member of the η Cha stellar kinematic group.
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 80606 and HD 80607 are two stars comprising a binary star system. They are approximately 217 light-years away in the constellation of Ursa Major. Both stars orbit each other at an average distance of 1,200 astronomical units. The binary system is listed as Σ1341 in the Struve Catalogue of Double Stars; however, this designation is not in wide use and the system is usually referred to by the HD designations of its constituent stars. An extrasolar planet has been confirmed to orbit HD 80606 in a highly elliptical orbit.
HD 219828 is a star with two exoplanetary companions in the constellation of Pegasus. With an apparent visual magnitude of 8.04, it is an eighth magnitude star that is too dim to be readily visible to the naked eye. The star is located at a distance of approximately 237 light years from the Sun based on parallax measurements, but is drifting closer with a radial velocity of −24 km/s.
HD 41004 is a visual binary star system in the southern constellation of Pictor. It is too faint to be visible to the naked eye, having a combined apparent visual magnitude of 8.65. The two components have a magnitude difference of 3.7, and share a common proper motion with an angular separation of 0.30″, as of 2018. The distance to this system is approximately 136 light years based on parallax. It is drifting further away from the Sun with a radial velocity of +42.5 km/s, having come to within 44.5 ly some 831,000 years ago.
HD 162020 is a star in the southern constellation of Scorpius with a likely red dwarf companion. It has an apparent visual magnitude of 9.10, which is too faint to be visible to the naked eye. The distance to this system is 101 light years based on stellar parallax. It is drifting closer to the Sun with a radial velocity of −27 km/s, and is predicted to come to within ~18 light-years in 1.1 million years.
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 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 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.
XO-2 is a binary star. It consists of two components: XO-2S and XO-2N.
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 86226 is a G-type yellowish white star found in the constellation of Hydra.
HD 40307 f is an extrasolar planet orbiting the star HD 40307. It is located 42 light-years away in the direction of the southern constellation Pictor. The planet was discovered by the radial velocity method, using the European Southern Observatory's HARPS apparatus by a team of astronomers led by Mikko Tuomi at the University of Hertfordshire and Guillem Anglada-Escude of the University of Göttingen, Germany. The existence of planet was confirmed in 2015.
HD 106515 is a binary star in the constellation of Virgo.
HD 109271 is a star in the constellation of Virgo. With an apparent magnitude of 8.05, it cannot be seen with the naked eye. Parallax measurements made by Gaia put the star at a distance of 182 light-years away.
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 20781 e is a hot Neptune around the star HD 20781. The planet has a minimum mass of 14.03 Earth masses and it orbits with a semi-major axis of 0.3374 astronomical units and an orbital eccentricity of approximately 0.06. With the same composition as Neptune, it would have a radius of 3.79 times that of the Earth. With the same composition as Earth, it would have a radius of 2.08 times that of the Earth. It orbits near the inner edge of the habitable zone of HD 20781.
HD 189567 is a G3V star located 58.5 light years away, in the constellation of Pavo. The star HD 189567 is also known as Gliese 776, CD-67 2385, and HR 7644.
References
- ↑ Roman, Nancy G. (1987). "Identification of a Constellation From a Position". Publications of the Astronomical Society of the Pacific. 99 (617): 695–699. Bibcode:1987PASP...99..695R. doi: 10.1086/132034 . Vizier query form
- 1 2 3 4 5 6 Vallenari, A.; et al. (Gaia Collaboration) (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics . arXiv: 2208.00211 . doi: 10.1051/0004-6361/202243940 . Gaia DR3 record for this source at VizieR.
- 1 2 3 4 5 6 7 8 9 Udry, S.; Dumusque, X.; et al. (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. S2CID 119095511.
- ↑ "HD 20781 -- High proper-motion Star". SIMBAD Astronomical Database. Centre de données astronomiques de Strasbourg . Retrieved 2014-09-10.
- 1 2 Desidera, S.; Barbieri, M. (January 2007). "Properties of planets in binary systems. The role of binary separation". Astronomy and Astrophysics . 462 (1): 345–353. arXiv: astro-ph/0610623 . Bibcode:2007A&A...462..345D. doi:10.1051/0004-6361:20066319. S2CID 13813761.
- ↑ "HD 20782". NASA Exoplanet Archive . Retrieved 12 November 2022.
- 1 2 Mayor, M.; Marmier, M.; et al. (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].
