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Gamma Cephei is a binary star system approximately 45 light-years away in the constellation of Cepheus. The primary is a stellar class K1 orange giant or subgiant star; it has a red dwarf companion. An exoplanet has been confirmed to be orbiting the primary.
HD 168443 is an ordinary yellow-hued star in the Serpens Cauda segment of the equatorial constellation of Serpens. It is known to have two substellar companions. With an apparent visual magnitude of 6.92, the star lies just below the nominal lower brightness limit of visibility to the normal human eye. This system is located at a distance of 127 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −48.7 km/s.
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 114762 is a triple star system approximately 125 light-years (38.2 pc) away in the constellation Coma Berenices. It consists of a yellow-white F-type main-sequence star (HD 114762 A) and two red dwarf companions (HD 114762 Ab & HD 114762 B) approximately 0.36 & 130 AU distant. Both are low-metal subdwarfs. Planets around such metal-poor stars are rare. A telescope or strong binoculars are needed to view the primary. HD 114762 had been used by scientists as a "standard star", one whose radial velocity is well established, but with the discovery of the spectroscopic companion HD 114762 Ab its usefulness as a standard has been called into question.
Gamma Cephei Ab, formally named Tadmor, is an exoplanet approximately 45 light-years away in the constellation of Cepheus. The planet was confirmed to be in orbit around Gamma Cephei A in 2002, but was first suspected to exist around 1988.
A Super-Earth is a type of exoplanet with a mass higher than Earth's, but substantially below those of the Solar System's ice giants, Uranus and Neptune, which are 14.5 and 17 times Earth's, respectively. The term "super-Earth" refers only to the mass of the planet, and so does not imply anything about the surface conditions or habitability. The alternative term "gas dwarfs" may be more accurate for those at the higher end of the mass scale, although "mini-Neptunes" is a more common term.
HD 11964 c is an extrasolar planet approximately 110 light-years away in the constellation of Cetus. The planet was discovered in a close-orbit around the yellow subgiant star HD 11964. The planet has a minimum mass 35 times the mass of Earth and is located in a mildly eccentric orbit which takes almost 38 days to complete. HD 11964 c was a possible planet discovered on the same day as HD 11964 b in 2005. HD 11964 c was first proposed in a paper published in 2007, and finally confirmed with new data presented in a review of multi-planet systems which appeared on the arXiv preprint website in 2008.
HD 154345 is a star in the northern constellation of Hercules. With an apparent visual magnitude of +6.76 it is a challenge to view with the naked eye, but using binoculars it is an easy target. The distance to this star is 59.6 light years based on parallax, but it is drifting closer with a radial velocity of −47 km/s. At least one exoplanet is orbiting this star.
HD 114762 b is a small red dwarf star, in the HD 114762 system, formerly thought to be a massive gaseous extrasolar planet, approximately 126 light-years (38.6 pc) away in the constellation of Coma Berenices. This optically undetected companion to the late F-type main-sequence star HD 114762 was discovered in 1989 by Latham, et al., and confirmed in an October 1991 paper by Cochran, et al. It was thought to be the first discovered exoplanet
HD 176051 is a spectroscopic binary star system approximately 49 light years away from Earth in the constellation Lyra. The pair orbit with a period of 22,423 days and an eccentricity of 0.25. Compared to the Sun, they have a somewhat lower proportion of elements more massive than helium. Their individual masses are estimated at 1.07 and 0.71 solar masses (M☉). The system is moving closer to the Sun with a radial velocity of −47 km/s and will reach perihelion in about 269,000 years when it comes within roughly 17 ly (5.1 pc) of the Sun.
HD 106252 is a star with a brown dwarf companion in the constellation Virgo. An apparent visual magnitude of 7.41 means this star is too faint to be visible to the naked eye. It is located at a distance of 210 light years from the Sun based on parallax measurements, and is receding with a radial velocity of 15 km/s.
HD 190228 is a star with a substellar companion in the constellation Vulpecula. Its apparent magnitude is 7.30 – too faint to be seen with the naked eye – and the absolute magnitude is 3.34. Based on parallax measurements, it is located at a distance of 205 light-years from the Sun. The star is older than the Sun with an age over 5 billion years and it is metal-poor.
HD 139357 is a 6th magnitude K-type giant star located approximately 370 light years from Earth, visible in the constellation Draco. Its mass is four thirds that of the Sun but its radius is 11.47 times larger. However, despite being a giant star, it is only 3.07 billion years old, which is younger than the Sun.
An exoplanet is a planet located outside the Solar System. The first evidence of an exoplanet was noted as early as 1917, but was not recognized as such until 2016; no planet discovery has yet come from that evidence. What turned out to be the first detection of an exoplanet was published among a list of possible candidates in 1988, though not confirmed until 2003. The first confirmed detection came in 1992, with the discovery of terrestrial-mass planets orbiting the pulsar PSR B1257+12. The first confirmation of an exoplanet orbiting a main-sequence star was made in 1995, when a giant planet was found in a four-day orbit around the nearby star 51 Pegasi. Some exoplanets have been imaged directly by telescopes, but the vast majority have been detected through indirect methods, such as the transit method and the radial-velocity method. As of 1 November 2023, there are 5,521 confirmed exoplanets in 4,070 planetary systems, with 885 systems having more than one planet. This is a list of the most notable discoveries.
References
- ↑ "NASA Exoplanet Archive" . Retrieved 20 December 2019.
- ↑ Campbell, Bruce; Walker, G. A. H.; Yang, S. (1988). "A Search for Substellar Companions to Solar-type Stars". The Astrophysical Journal. 331: 902. Bibcode:1988ApJ...331..902C. doi: 10.1086/166608 .
- ↑ Hatzes, Artie P.; et al. (2003). "A Planetary Companion to Gamma Cephei A". The Astrophysical Journal. 599 (2): 1383–1394. arXiv: astro-ph/0305110 . Bibcode:2003ApJ...599.1383H. doi:10.1086/379281. S2CID 11506537.
- ↑ "The planet-host star Iota Horologii".
- ↑ Kiefer, Flavien (17 October 2019). "Determining the mass of the planetary candidate HD 114762 b using Gaia". Astronomy & Astrophysics. 632: L9. arXiv: 1910.07835 . Bibcode:2019A&A...632L...9K. doi:10.1051/0004-6361/201936942. S2CID 204743831.
