Related Research Articles
Hercules is a constellation named after Hercules, the Roman mythological hero adapted from the Greek hero Heracles. Hercules was one of the 48 constellations listed by the second-century astronomer Ptolemy, and it remains one of the 88 modern constellations today. It is the fifth-largest of the modern constellations and is the largest of the 50 which have no stars brighter than apparent magnitude +2.5.
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.
HD 155358 is a low metallicity yellow dwarf star approximately 43 pc away in the constellation Hercules. This star is known to be orbited by two extrasolar planets.
HD 164922 b is an exoplanet orbiting the star HD 164922 about 72 light-years from Earth in the constellation Hercules. Its inclination is not known, and its true mass may be significantly greater than the radial velocity lower limit of 0.36 Jupiter masses. The planet also has a low eccentricity, unlike most other long period extrasolar planets – 0.05 – about the same as Jupiter and Saturn in the Solar System. 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.
HD 175541 is an 8th magnitude star with an exoplanetary companion in the constellation Serpens. It has the proper name Kaveh, which was selected by Iran during the NameExoWorlds campaign as part of the 100th anniversary of the IAU. Kaveh is one of the heroes of Shahnameh. The apparent visual magnitude of 8.02 is too faint for this star to be visible in the naked eye. It is located at a distance of approximately 424 light years from the Sun based on parallax measurements, and is drifting further away with a radial velocity of +20 km/s. Despite its distance, it was given the number 736 in the Gliese Catalogue of Nearby Stars.
HD 192699 is a yellow subgiant star located approximately 214 light-years away in the constellation of Aquila. It has the apparent magnitude of 6.45. Based on its mass of 1.68 solar, it was an A-type star when it was a main-sequence. In April 2007, a planet was announced orbiting the star, together with HD 175541 b and HD 210702 b.
HD 192699 b, also named Khomsa, is an exoplanet located approximately 214 light-years away in the constellation of Aquila, orbiting the star HD 192699. This planet was discovered in April 2007, massing at least 2.5 times the mass of Jupiter (MJ). Despite its orbital distance more than that of Earth, the orbital period is less than a year, because the parent star is more massive than the Sun.
HD 210702 b is an exoplanet located approximately 177 light-years away in the constellation of Pegasus, orbiting the star HD 210702. This planet, together with HD 175541 b and HD 192699 b, are planets around intermediate mass stars that were announced in April 2007 by Johnson et al. It has at least twice the mass of Jupiter and it orbits with semimajor axis of 1.17 AU, corresponding to a period of 341.1 days.
HD 175541 b, also named Kavian, is a jovian planet located approximately 424 light-years away in the constellation of Serpens, orbiting the star HD 175541. This planet was discovered in April 2007. Despite the distance of planet to star slightly more than Earth to the Sun, the period is less than 300 days that orbits in an eccentric orbit, because the parent star is 65% more massive than the Sun.
HD 155358 c is an extrasolar planet orbiting the star HD 155358 located 142 light years away in the constellation Hercules. This is a gas giant which orbits at 1.224 AU and takes 530.3 days to orbit HD 155358. This planet orbits in an eccentric orbit. This planet has at least half the mass of Jupiter.
HD 154672 is a yellow subgiant. It is about 65 parsecs away from the Sun that is larger than, but of a similar mass to, the Sun. However, HD 154672 is much older. The star is very metal-rich, which is one of the reasons why it was targeted for a planet search by the N2K Consortium, which discovered the gas giant planet HD 154672 b using Doppler Spectroscopy; the discovery was reported in October 2008. The N2K collaboration chose HD 154672 primarily because it aimed to discover the correlation between a star's metallicity and the mass of orbiting planets.
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 205739 b is an extrasolar planet located approximately 350 light-years away.
HD 153950 b, also known as Trimobe, is an extrasolar planet located approximately 162 light-years away. This planet was discovered on October 26, 2008 by Moutou et al. using the HARPS spectrograph on ESO's 3.6 meter telescope installed at La Silla Observatory in Atacama desert, Chile.
HD 79498 is a double star in the northern constellation of Cancer. The primary component of this pair has an orbiting exoplanet companion. This star is too faint to be viewed with the naked eye, having an apparent visual magnitude of 8.05. The system is located at a distance of 159 light years based on parallax measurements, and is drifting further away with a heliocentric radial velocity of 20 km/s. It has a relatively high proper motion, traversing the celestial sphere at an angular rate of 0.2″·yr−1.
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 an oddity; 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 220773 is a 7th-magnitude star approximately 165 light years away in the constellation of Pegasus.
HD 219134 g, also known as HR 8832 g, is an unconfirmed exoplanet orbiting around the K-type star HD 219134 in the constellation of Cassiopeia. It has a minimum mass of 11 or 15 Earth masses, suggesting that it is likely a Neptune-like ice giant. Unlike HD 219134 b and HD 219134 c it is not observed to transit and thus its radius and density are unknown. If it has an Earth-like composition, it would have a radius 1.9 times that of Earth. However, since it is probably a Neptune-like planet, it is likely larger.
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.
HD 131496 is an evolved subgiant star in the constellation Boötes. With an apparent visual magnitude of 7.9 it is too faint to be visible to the naked eye. Stars like HD 131496 are sometimes referred to as "retired A-stars", since they would have been A-type stars while on the main sequence. This name is most commonly used in connection with the search for extrasolar planets, where they are useful because these evolved stars are cooler and have more spectral lines than their main sequence counterparts, making planet detection easier.
References
- Cochran, W.; et al. (2007). "A Planetary System Around HD 155358: The Lowest Metallicity Planet Host Star". The Astrophysical Journal. 665 (2): 1407–1412. arXiv: 0705.3228 . Bibcode:2007ApJ...665.1407C. doi:10.1086/519555. S2CID 14591389.
