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HD 219134
HD 219134 (also known as Gliese 892 or HR 8832) is a main-sequence star in the constellation of Cassiopeia. It is smaller and less luminous than the Sun, with a spectral class of K3V, which makes it an orange-hued star. HD 219134 is relatively close to our system, with an estimated distance of 21.34 light years. This star is close to the limit of apparent magnitude that can still be seen by the unaided eye. The limit is considered to be magnitude 6 for most observers. This star has a magnitude 9.4 optical companion at an angular separation of 106.6 arcseconds. Planetary system HD 219134 has a system of six known exoplanets. The innermost planet, HD 219134 b, is a rocky super-Earth based on size (1.6 times the size of Earth), and density (6.4 grams per cubic cm). This and three additional exoplanets; one super-Earth (designated ''c'' and later found to be rocky as well), one Neptunian world (''d''), and one Jovian world (''e''); were deduced using HARPS-N radial vel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exoplanet
An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917 but was not recognized as such. The first confirmation of detection occurred in 1992. A different planet, initially detected in 1988, was confirmed in 2003. There are many methods of detecting exoplanets. Transit photometry and Doppler spectroscopy have found the most, but these methods suffer from a clear observational bias favoring the detection of planets near the star; thus, 85% of the exoplanets detected are inside the tidal locking zone. In several cases, multiple planets have been observed around a star. About 1 in 5 Sun-like starsFor the purpose of this 1 in 5 statistic, "Sun-like" means G-type star. Data for Sun-like stars was not available so this statistic is an extrapolation from data about K-type stars. have an "Earth-sized"For the purpose of this 1 in 5 statistic, Earth-sized means 1–2 Earth radii. planet in the habitable zone. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ExoKyoto
ExoKyoto is a database written in C++ that includes over 3,500 confirmed exoplanets as well as more than 120,000 stars. The database is led by Professor Yosuke Yamashiki of the Graduate School of Advanced Leadership Studies, at Kyoto University. ExoKyoto is particularly useful to visualize the habitable zone of different stars and compare their planets with the Solar System in terms of irradiance. Together with the Extrasolar Planets Encyclopaedia, the NASA Exoplanet Archive, the Open Exoplanet Catalogue, and the Exoplanet Data Explorer, ExoKyoto is a popular exoplanet database that is widely used. See also *NASA Exoplanet Archive The NASA Exoplanet Archive is an online astronomical exoplanet catalog and data service that collects and serves public data that support the search for and characterization of extra-solar planets (exoplanets) and their host stars. It is part of ... References Databases in Japan Astronomical databases {{Astronomy-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Circumstellar Habitable Zone
In astronomy and astrobiology, the circumstellar habitable zone (CHZ), or simply the habitable zone, is the range of orbits around a star within which a planetary surface can support liquid water given sufficient atmospheric pressure.J. F. Kasting, D. P. Whitmire, R. T. Reynolds, Icarus 101, 108 (1993). The bounds of the CHZ are based on Earth's position in the Solar System and the amount of radiant energy it receives from the Sun. Due to the importance of liquid water to Earth's biosphere, the nature of the CHZ and the objects within it may be instrumental in determining the scope and distribution of planets capable of supporting Earth-like extraterrestrial life and intelligence. The habitable zone is also called the Goldilocks zone, a metaphor, allusion and antonomasia of the children's fairy tale of " Goldilocks and the Three Bears", in which a little girl chooses from sets of three items, ignoring the ones that are too extreme (large or small, hot or cold, etc.), and set ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HD 219134 H
HD 219134 h, also known as HR 8832 h, is an exoplanet orbiting around the K-type star HD 219134 in the constellation of Cassiopeia. It has a minimum mass of 108 Earth masses, which indicates that the planet is likely a gas giant. Unlike HD 219134 b HD 219134 b (or HR 8832 b) is one of at least five exoplanets orbiting HD 219134, a main-sequence star in the constellation of Cassiopeia. HD 219134 b has a size of about 1.6 , and a density of 6.4 g/cm3 and orbits at 21.25 light-years away. ... and c it is not observed to transit and thus its radius and density are unknown. This planet was initially reported in two 2015 papers; one referred to it as HD 219134 e, while the other found different, and more accurate, parameters for it and so treated it as a different planet, designated HD 219134 h. It is now generally referred to by the HD 219134 h designation. References {{Extrasolar-planet-stub Cassiopeia (constellation) Exoplanets discovered in 2015 Exoplanets detected b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HD 219134 G
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. Characteristics Mass, Radius, and Temperature HD 219134 g is a sub-Neptune-mass exoplanet with a minimum mass of and an unknown radius, as it is not known to transit. However, due to the high metal content of the host star, the planet might not be an ice giant. For a rock-iron composition, HD 219134 g would be about 1.9 , which seems unlikely for a planet of this mass. A more plausible rock-water composition would put the planet at about 2.4 . Assuming an albedo of 0.3, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HD 219134 D
HD 219134 d, also known as HR 8832 d, is an exoplanet orbiting around the K-type star HD 219134 in the constellation of Cassiopeia. It has a minimum mass over 16 times that of Earth, indicating that it is likely a Hot Neptune. The exoplanet was initially detected by the instrument HARPS-N of the Italian Telescopio Nazionale Galileo via the radial velocity method. Unlike HD 219134 b and HD 219134 c it was not observed by the Spitzer Space Telescope and thus its radius and density are unknown. Only a minimum possible radius can be given. Characteristics Mass, radius, and temperature HD 219134 d is a likely ice giant, with a minimum mass of 16.17 , comparable to that of Neptune. However, because it has not been found to transit its host star, the planet's true mass and radius are unknown. Gillion ''et al'' predicts a minimum possible radius of 1.61 , equivalent with a pure iron composition similar to that of K2-3d. However, such a composition is highly unlikely for a planet of thi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HD 219134 F
HD 219134 f, also known as HR 8832 f, is an exoplanet orbiting around the K-type star HD 219134 in the constellation of Cassiopeia. It is a Super-Earth with a minimum mass of over 7 times that of Earth. Unlike HD 219134 b and HD 219134 c it was not observed by the Spitzer Space Telescope and thus its radius and density are unknown. Only a minimum radius can be given. Characteristics Mass, Radius, and Temperature HD 219134 f is known as a Super-Earth, a planet that's more massive than Earth but less massive than Uranus or Neptune. However, because it is not known to transit its star, only the minimum mass can be determined. The planet is at least 7.30 , indicating that it could be anything from a dense rocky planet to a low-density ice giant. Gillon et al. gives the planet a minimum radius of about 1.31 , which would result in an almost impossible density. For a more likely mixed composition of rock, water, and hydrogen, HD 219134 f would have a radius closer to about 2.10 . Bei ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HD 219134 C
HD 219134 c, also known as HR 8832 c, is a hot, dense, rocky exoplanet orbiting around the K-type star HD 219134 in the constellation of Cassiopeia. Originally thought to be a little less than three times the mass of Earth, it is now known to be over 4 times the mass and 51% larger in radius, suggesting a rocky composition with a higher quantity of iron than Earth. The exoplanet was initially detected by the instrument HARPS-N of the Italian Telescopio Nazionale Galileo via the radial velocity method. Transits of the planet were observed by the Spitzer Space Telescope in 2017. Later that year, it was predicted that HD 219134 c has an atmosphere. Characteristics Mass, radius, and temperature HD 219134 c is confirmed to be a rocky super-Earth, meaning that it has a solid surface but is significantly larger than Earth. The mass of the planet has been determined to be around 4.36 with very low uncertainty. Its radius was found to be 1.511 (9,627 km), once again with a small ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Harvard
Harvard University is a private Ivy League research university in Cambridge, Massachusetts. Founded in 1636 as Harvard College and named for its first benefactor, the Puritan clergyman John Harvard, it is the oldest institution of higher learning in the United States and one of the most prestigious and highly ranked universities in the world. The university is composed of ten academic faculties plus Harvard Radcliffe Institute. The Faculty of Arts and Sciences offers study in a wide range of undergraduate and graduate academic disciplines, and other faculties offer only graduate degrees, including professional degrees. Harvard has three main campuses: the Cambridge campus centered on Harvard Yard; an adjoining campus immediately across Charles River in the Allston neighborhood of Boston; and the medical campus in Boston's Longwood Medical Area. Harvard's endowment is valued at $50.9 billion, making it the wealthiest academic institution in the world. Endowment inco ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jovian Planet
The giant planets constitute a diverse type of planet much larger than Earth. They are usually primarily composed of low-boiling-point materials (volatiles), rather than rock or other solid matter, but massive solid planets can also exist. There are four known giant planets in the Solar System: Jupiter, Saturn, Uranus and Neptune. Many extrasolar giant planets have been identified orbiting other stars. They are also sometimes called jovian planets, after Jupiter ("Jove" being another name for the Roman god "Jupiter"). They are also sometimes known as gas giants. However, many astronomers now apply the latter term only to Jupiter and Saturn, classifying Uranus and Neptune, which have different compositions, as ice giants. Both names are potentially misleading: all of the giant planets consist primarily of fluids above their critical points, where distinct gas and liquid phases do not exist. The principal components are hydrogen and helium in the case of Jupiter and Saturn, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ice Giant
An ice giant is a giant planet composed mainly of elements heavier than hydrogen and helium, such as oxygen, carbon, nitrogen, and sulfur. There are two ice giants in the Solar System: Uranus and Neptune. In astrophysics and planetary science the term "ices" refers to volatile chemical compounds with freezing points above about 100 K, such as water, ammonia, or methane, with freezing points of 273 K (0°C), 195 K (−78°C), and 91 K (−182°C), respectively (see Volatiles). In the 1990s, it was determined that Uranus and Neptune are a distinct class of giant planet, separate from the other giant planets, Jupiter and Saturn, which are gas giants predominantly composed of hydrogen and helium. As such, Neptune and Uranus are now referred to as ''ice giants''. Lacking well defined solid surfaces, they are primarily composed of gases and liquids. Their constituent compounds were solids when they were primarily incorporated into the planets during their format ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
