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AB Doradus Moving Group
AB Doradus Moving Group is a group of about 30 associated stars that are moving through space together with the star AB Doradus. A moving group is distinguished by its members having about the same age, composition (or metallicity) and motion through space. Hence they most likely formed in the same location. This group is located about 20 parsecs from the Earth and is the closest known co-moving group. The average space velocity of this group has components of U = −8, V = −27 and W = −14 km/s. About 10 of these stars form a nuclear group within a volume roughly 10 parsecs across. The proximity of this moving group makes it useful for studies of shared stellar properties, as well as detection of companions through direct imaging. These can be used for refinement of young stellar models, for example. Age The age of the AB Dor Moving Group has been somewhat controversial, with quoted ages in the range of ~50 to ~150 Myr; recent work, however ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
AB Doradus
AB Doradus is a pre-main-sequence quadruple star system in the constellation Dorado. The primary is a flare star that shows periodic increases in activity. The primary star in this system spins at a rate 50 times that of the Sun, and consequently has a strong magnetic field. It has a greater number of star spots than the Sun. These can cause the luminosity of the star to appear to vary over each orbital cycle. Measurements of the spin rate of this star at its equator have shown that it varies over time due to the effect of this magnetic field. The system has four components consisting of a pair of binary star systems separated by an angle of about 9″. The binary star AB Doradus Ba/Bb orbits the primary AB Doradus A at an average distance of 135 astronomical units (AUs). AB Doradus C is a closer in companion that orbits the primary at a distance of 5.1 AU, and has an orbital period of 11.75 years. AB Doradus C is among the lowest-mass stars ever found. At an esti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CFBDSIR 2149−0403
CFBDSIR 2149-0403 (full designation CFBDSIR J214947.2-040308.9) is a free-floating planetary-mass object or possibly a high- metallicity, low-mass brown dwarf in the constellation Aquarius. Originally, it was thought to be part of the AB Doradus moving group (ABDMG) as indicated by its position and proper motion, but the same team that discovered the object and conjectured its membership in the group has now rejected that hypothesis due to newer measurements. Without that membership, the age and mass of the object cannot be constrained. There is insufficient evidence to demonstrate that CFBDSIR 2149-0403 formed as a planet and was subsequently ejected. Discovery CFBDSIR 2149-0403 was discovered by the Canada-France Brown Dwarfs Survey, a near-infrared sky survey, and confirmed by WISE data. Philippe Delorme, of the Institute of Planetology and Astrophysics of Grenoble in France and his team, including researchers at Université de Montréal in Canada, detected CFBDSIR2149 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
TW Hydrae Association
The TW Hydrae association is a group of very young low-mass stars and substellar objects located approximately 25–75 parsecs (80–240 light years) from Earth. They share a common motion and appear to all be roughly the same age, 10±3 million years old. It is the youngest such association within 100 pc from Earth. As of 2017, 42 objects (in 23 systemsSingular objects are also regarded as "systems" here.) are assigned to the association confidently, and several dozens — uncertainly. Masses of its known members vary from 5 Jupiter masses to 2 solar masses, and their spectral types vary from A0 to L7. Some of the best studied members of this stellar association are TW Hydrae (nearest known accreting T Tauri star to the Earth), HR 4796 (an A-type star with resolved dusty debris disk; the most massive known group member), HD 98800 (a quadruple star system with debris disk), and 2M1207 (accreting brown dwarf with remarkable planetary-mass companion 2M1207b). Included in the assoc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beta Pictoris Moving Group
The Beta Pictoris Moving Group is a young moving group of stars located relatively near Earth. A moving group, in astronomy, is a group of stars that share a common motion through space as well as a common origin. This moving group is named for Beta Pictoris. The Beta Pictoris Moving Group is an important object for astronomical study as it is the closest youthful group of stars to the Earth. The star Beta Pictoris is known to have a large disk of gas and dust, possibly a protoplanetary disk. There is also evidence of a young gas giant planet around the star. A free-floating planet has also been found in the moving group, PSO J318.5-22. The age and distance of the group makes it a candidate for directly imaging extrasolar planets. Constituents The Beta Pictoris Moving Group consists of 17 stellar systems, comprising a total of 28 individual component stars, including identified brown dwarfs. The core of the group is located some 115 light-years from Earth, and has an average ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Nearby Stellar Associations And Moving Groups ...
This is a list of nearby stellar associations and moving groups. A stellar association is a very loose star cluster, looser than an open cluster. A moving group is the remnant of such a stellar association. Members of stellar associations and moving groups share similar kinematic properties, as well as similar ages and chemical composition. ''The list is sorted by the distance to the Solar System.'' See also * List of stellar streams *List of open clusters *List of nearest stars and brown dwarfs References {{Portal bar, Astronomy, Stars, Spaceflight, Outer space, Solar System Stellar associations A stellar association is a very loose star cluster, looser than both open clusters and globular clusters. Stellar associations will normally contain from 10 to 100 or more stars. The stars share a common origin, but have become gravitationally u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2MASS J22362452+4751425
Mass is an intrinsic property of a body. It was traditionally believed to be related to the quantity of matter in a physical body, until the discovery of the atom and particle physics. It was found that different atoms and different elementary particles, theoretically with the same amount of matter, have nonetheless different masses. Mass in modern physics has multiple definitions which are conceptually distinct, but physically equivalent. Mass can be experimentally defined as a measure of the body's inertia, meaning the resistance to acceleration (change of velocity) when a net force is applied. The object's mass also determines the strength of its gravitational attraction to other bodies. The SI base unit of mass is the kilogram (kg). In physics, mass is not the same as weight, even though mass is often determined by measuring the object's weight using a spring scale, rather than balance scale comparing it directly with known masses. An object on the Moon would weigh l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Super-jupiter
A super-Jupiter is a gas giant exoplanet that is more massive than the planet Jupiter. For example, companions at the planet–brown dwarf borderline have been called super-Jupiters, such as around the star Kappa Andromedae. By 2011 there were 180 known super-Jupiters, some hot, some cold. Even though they are more massive than Jupiter, they remain about the same size as Jupiter up to 80 Jupiter masses. This means that their surface gravity and density go up proportionally to their mass. The increased mass compresses the planet due to gravity, thus keeping it from being larger. In comparison, planets somewhat lighter than Jupiter can be larger, so-called "puffy planets" (gas giants with a large diameter but low density). An example of this may be the exoplanet HAT-P-1b with about half the mass of Jupiter but about 1.38 times larger diameter. CoRoT-3b, with a mass around 22 Jupiter masses, is predicted to have an average density of 26.4 g/cm3, greater than osmium (22.6 g/cm3) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GU Piscium
GU Piscium is a star in the constellation Pisces. An RS Canum Venaticorum variable, it ranges from magnitude 12.96 to 13.24 over 1.04 days. It is 48 Parsecs (155 light-years) distant from Earth. This star is also believed to be a member of the AB Doradus moving group with a membership probability of 96.9%. In 2014, it was found to have a gas giant A gas giant is a giant planet composed mainly of hydrogen and helium. Gas giants are also called failed stars because they contain the same basic elements as a star. Jupiter and Saturn are the gas giants of the Solar System. The term "gas giant" ... planet— GU Piscium b—orbiting it. References {{DEFAULTSORT:GU Piscium Pisces (constellation) M-type main-sequence stars RS Canum Venaticorum variables Piscium, GU ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GU Piscium B
GU Piscium b (GU Psc b) is a directly imaged planetary-mass companion orbiting the star GU Piscium, with an extremely large orbit of , and an apparent angular separation of 42 arc seconds. The planet is located at right ascension declination at a distance of . Properties An orbital revolution around its parent star (which is 1/3 the mass of the Sun) or "year", would take approximately 163,000 years to complete, considering a circular orbit with 2000 AU as the semi-major axis. It is a gas giant located in the constellation of Pisces, 155 light-years from the Solar System, and estimated to have a mass nine to thirteen times that of Jupiter, and a surface temperature of 1000 K. It is a relatively young stellar system, part of the AB Doradus moving group of ca. 30 main stars created from the same molecular cloud less than 100 million years ago, and the only one found among the 90 stars of the group examined. Discovery The discovery was made by an international team ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2MASS J01225093-2439505
Mass is an intrinsic property of a body. It was traditionally believed to be related to the quantity of matter in a physical body, until the discovery of the atom and particle physics. It was found that different atoms and different elementary particles, theoretically with the same amount of matter, have nonetheless different masses. Mass in modern physics has multiple definitions which are conceptually distinct, but physically equivalent. Mass can be experimentally defined as a measure of the body's inertia, meaning the resistance to acceleration (change of velocity) when a net force is applied. The object's mass also determines the strength of its gravitational attraction to other bodies. The SI base unit of mass is the kilogram (kg). In physics, mass is not the same as weight, even though mass is often determined by measuring the object's weight using a spring scale, rather than balance scale comparing it directly with known masses. An object on the Moon would weigh l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Super-Jupiter
A super-Jupiter is a gas giant exoplanet that is more massive than the planet Jupiter. For example, companions at the planet–brown dwarf borderline have been called super-Jupiters, such as around the star Kappa Andromedae. By 2011 there were 180 known super-Jupiters, some hot, some cold. Even though they are more massive than Jupiter, they remain about the same size as Jupiter up to 80 Jupiter masses. This means that their surface gravity and density go up proportionally to their mass. The increased mass compresses the planet due to gravity, thus keeping it from being larger. In comparison, planets somewhat lighter than Jupiter can be larger, so-called "puffy planets" (gas giants with a large diameter but low density). An example of this may be the exoplanet HAT-P-1b with about half the mass of Jupiter but about 1.38 times larger diameter. CoRoT-3b, with a mass around 22 Jupiter masses, is predicted to have an average density of 26.4 g/cm3, greater than osmium (22.6 g/cm3) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Planet
A planet is a large, rounded astronomical body that is neither a star nor its remnant. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a young protostar orbited by a protoplanetary disk. Planets grow in this disk by the gradual accumulation of material driven by gravity, a process called accretion. The Solar System has at least eight planets: the terrestrial planets Mercury, Venus, Earth and Mars, and the giant planets Jupiter, Saturn, Uranus and Neptune. These planets each rotate around an axis tilted with respect to its orbital pole. All of them possess an atmosphere, although that of Mercury is tenuous, and some share such features as ice caps, seasons, volcanism, hurricanes, tectonics, and even hydrology. Apart from Venus and Mars, the Solar System planets generate magnetic fields, and all except Venus and Mercury have natural satellites. The giant planets ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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