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Flora Asteroid
The Flora family (''adj. Florian''; ; also known as ''Ariadne family'') is a prominent family of stony asteroids located in the inner region of the asteroid belt. It is one of the largest families with more than 13,000 known members, or approximately 3.5% of all main-belt asteroids. The origin and properties of this family are relatively poorly understood. It is a very broad family which gradually fades into the surrounding background population. While the largest members, 8 Flora and 43 Ariadne, are located near the edge, there are several distinct groupings within the family, possibly created by later, secondary collisions. Due to this complex internal structure and the poorly defined boundaries, the Flora family has also been described as an asteroid clan. Only few interlopers have been identified. This family may be the source of the impactor that formed the Chicxulub crater, the likely culprit in the extinction of the dinosaurs. Characteristics The largest ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flora Family
The Flora family (''adj. Florian''; ; also known as ''Ariadne family'') is a prominent family of stony asteroids located in the inner region of the asteroid belt. It is one of the largest families with more than 13,000 known members, or approximately 3.5% of all main-belt asteroids. The origin and properties of this family are relatively poorly understood. It is a very broad family which gradually fades into the surrounding background population. While the largest members, 8 Flora and 43 Ariadne, are located near the edge, there are several distinct groupings within the family, possibly created by later, secondary collisions. Due to this complex internal structure and the poorly defined boundaries, the Flora family has also been described as an asteroid clan. Only few interlopers have been identified. This family may be the source of the impactor that formed the Chicxulub crater, the likely culprit in the extinction of the dinosaurs. Characteristics The larg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
43 Ariadne
Ariadne (minor planet designation: 43 Ariadne) is a fairly large and bright main-belt asteroid. It is the second-largest member of the Flora asteroid family. It was discovered by N. R. Pogson on 15 April 1857 and named after the Greek heroine Ariadne. Characteristics Ariadne is very elongate (almost twice as long as its smallest dimension) and probably bi-lobed or at least very angular. It is a retrograde rotator, although its pole points almost parallel to the ecliptic towards ecliptic coordinates (β, λ) = (−15°, 253°) with a 10° uncertainty. This gives an axial tilt of about 105°. Studies 43 Ariadne was in a study of asteroids using the Hubble FGS. Asteroids studied include (63) Ausonia, (15) Eunomia, (43) Ariadne, (44) Nysa, and (624) Hektor. Trivia * For reasons unknown, "Asteroid 43 Ariadne" was included in a list of names of supporters of the NASA spacecraft Stardust that was stored on a microchip within the spacecraft. * The maximum apparent size of Ariad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Semi-major Axis
In geometry, the major axis of an ellipse is its longest diameter: a line segment that runs through the center and both foci, with ends at the two most widely separated points of the perimeter. The semi-major axis (major semiaxis) is the longest semidiameter or one half of the major axis, and thus runs from the centre, through a focus, and to the perimeter. The semi-minor axis (minor semiaxis) of an ellipse or hyperbola is a line segment that is at right angles with the semi-major axis and has one end at the center of the conic section. For the special case of a circle, the lengths of the semi-axes are both equal to the radius of the circle. The length of the semi-major axis of an ellipse is related to the semi-minor axis's length through the eccentricity and the semi-latus rectum \ell, as follows: The semi-major axis of a hyperbola is, depending on the convention, plus or minus one half of the distance between the two branches. Thus it is the distance from the center ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proper Orbital Elements
__NOTOC__ The proper orbital elements or proper elements of an orbit are constants of motion of an object in space that remain practically unchanged over an astronomically long timescale. The term is usually used to describe the three quantities: *''proper semimajor axis'' (''ap''), *''proper eccentricity'' (''ep''), and *''proper inclination'' (''ip''). The proper elements can be contrasted with the osculating Keplerian orbital elements observed at a particular time or epoch, such as the semi-major axis, eccentricity, and inclination. Those osculating elements change in a quasi-periodic and (in principle) predictable manner due to such effects as perturbations from planets or other bodies, and precession (e.g. perihelion precession). In the Solar System, such changes usually occur on timescales of thousands of years, while proper elements are meant to be practically constant over at least tens of millions of years. For most bodies, the osculating elements are relatively close ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vincenzo Zappalà
Vincenzo Zappalà (born 1945) is an Italian astronomer and discoverer of several main-belt asteroids. He is credited by the Minor Planet Center with the discovered of 9 minor planets. All of his discoveries he made at ESO's Chilean La Silla Observatory in 1984, with the exception of 17357 Lucataliano, which he discovered at Mount Stromlo Observatory in 1978. He has also been a long-term astronomer at the Observatory of Turin in Pino Torinese. Awards and honors The main-belt asteroid 2813 Zappalà, discovered by American astronomer Edward Bowell at the U.S. Anderson Mesa Station in 1981, is named in his honour. List of discovered minor planets See also * * Zoran Knežević (astronomer) Zoran Knežević ( sr-cyr, Зоран Кнежевић, born 23 August 1949 in Osijek) is a Serbian astronomer, who has been publishing since 1982. His major scientific contributions are in the field of movement of small Solar System bodies, thei ... References Externa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hierarchical Clustering Method
An asteroid family is a population of asteroids that share similar proper orbital elements, such as semimajor axis, eccentricity, and orbital inclination. The members of the families are thought to be fragments of past asteroid collisions. An asteroid family is a more specific term than asteroid group whose members, while sharing some broad orbital characteristics, may be otherwise unrelated to each other. General properties Large prominent families contain several hundred recognized asteroids (and many more smaller objects which may be either not-yet-analyzed, or not-yet-discovered). Small, compact families may have only about ten identified members. About 33% to 35% of asteroids in the main belt are family members. There are about 20 to 30 reliably recognized families, with several tens of less certain groupings. Most asteroid families are found in the main asteroid belt, although several family-like groups such as the Pallas family, Hungaria family, and the Phocaea family ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surface is made up of the ocean, dwarfing Earth's polar ice, lakes, and rivers. The remaining 29% of Earth's surface is land, consisting of continents and islands. Earth's surface layer is formed of several slowly moving tectonic plates, which interact to produce mountain ranges, volcanoes, and earthquakes. Earth's liquid outer core generates the magnetic field that shapes the magnetosphere of the Earth, deflecting destructive solar winds. The atmosphere of the Earth consists mostly of nitrogen and oxygen. Greenhouse gases in the atmosphere like carbon dioxide (CO2) trap a part of the energy from the Sun close to the surface. Water vapor is widely present in the atmosphere and forms clouds that cover most of the planet. More solar e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hirayama Families
A Hirayama family of asteroids is a group of minor planets that share similar orbital elements, such as semimajor axis, eccentricity, and orbital inclination. The members of the families are thought to be fragments of past asteroid collisions. Strictly speaking, families and their membership are identified by analysing the so-called proper orbital elements rather than the current osculating orbital elements, which regularly fluctuate on timescales of tens of thousands of years. The ''proper elements'' are related constants of motion that are thought to remain almost constant for times of at least tens of millions of years. The Japanese astronomer Kiyotsugu Hirayama (1874–1943) pioneered the estimation of proper elements for asteroids, and first identified several of the most prominent families in 1918. Kiyotsugu Hirayama initially identified the Koronis, Eos, and Themis families, and later recognized also the Flora and Maria Maria may refer to: People * Mary, mother of Je ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Secular Resonance
A secular resonance is a type of orbital resonance between two bodies with synchronized precessional frequencies. In celestial mechanics, secular refers to the long-term motion of a system, and resonance is periods or frequencies being a simple numerical ratio of small integers. Typically, the synchronized precessions in secular resonances are between the rates of change of the argument of the periapses or the rates of change of the longitude of the ascending nodes of two system bodies. Secular resonances can be used to study the long-term orbital evolution of asteroids and their families within the asteroid belt. Description Secular resonances occur when the precession of two orbits is synchronised (a precession of the perihelion, with frequency g, or the ascending node, with frequency s, or both). A small body (such as a small Solar System body) in secular resonance with a much larger one (such as a planet) will precess at the same rate as the large body. Over relatively shor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
L Chondrite
The L type ordinary chondrites are the second most common group of meteorites, accounting for approximately 35% of all those catalogued, and 40% of the ordinary chondrites. The ordinary chondrites are thought to have originated from three parent asteroids, with the fragments making up the H chondrite, L chondrite and LL chondrite groups respectively. Name Their name comes from their relatively low iron abundance, with respect to the H chondrites, which are about 20–25% iron by weight. Historically, the L chondrites have been named ''hypersthene chondrites'' or ''olivine hypersthene chondrites'' for the dominant minerals, but these terms are now obsolete. Chemical composition Characteristic is the fayalite content (Fa) in olivine of 21 to 25 mol%. About 4–10% iron–nickel is found as a free metal, making these meteorites magnetic, but not as strongly as the H chondrites. Mineralogy The most abundant minerals are olivine and hypersthene (an orthopyroxene), as well as ir ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Olivine
The mineral olivine () is a magnesium iron silicate with the chemical formula . It is a type of nesosilicate or orthosilicate. The primary component of the Earth's upper mantle, it is a common mineral in Earth's subsurface, but weathers quickly on the surface. For this reason, olivine has been proposed as a good candidate for accelerated weathering to sequester carbon dioxide from the Earth's oceans and atmosphere, as part of climate change mitigation. Olivine also has many other historical uses, such as the gemstone peridot (or chrysolite), as well as industrial applications like metalworking processes. The ratio of magnesium to iron varies between the two endmembers of the solid solution series: forsterite (Mg-endmember: ) and fayalite (Fe-endmember: ). Compositions of olivine are commonly expressed as molar percentages of forsterite (Fo) and fayalite (Fa) (''e.g.'', Fo70Fa30). Forsterite's melting temperature is unusually high at atmospheric pressure, almost , while ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Planetary Differentiation
In planetary science, planetary differentiation is the process by which the chemical elements of a planetary body accumulate in different areas of that body, due to their physical or chemical behavior (e.g. density and chemical affinities). The process of planetary differentiation is mediated by partial melting with heat from radioactive isotope decay and planetary accretion. Planetary differentiation has occurred on planets, dwarf planets, the asteroid 4 Vesta, and natural satellites (such as the Moon). Physical differentiation Gravitational separation High-density materials tend to sink through lighter materials. This tendency is affected by the relative structural strengths, but such strength is reduced at temperatures where both materials are plastic or molten. Iron, the most common element that is likely to form a very dense molten metal phase, tends to congregate towards planetary interiors. With it, many siderophile elements (i.e. materials that readily alloy with iron) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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