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N-body
In physics and astronomy, an ''N''-body simulation is a simulation of a dynamical system of particles, usually under the influence of physical forces, such as gravity (see ''n''-body problem for other applications). ''N''-body simulations are widely used tools in astrophysics, from investigating the dynamics of few-body systems like the Earth-Moon-Sun system to understanding the evolution of the large-scale structure of the universe. In physical cosmology, ''N''-body simulations are used to study processes of non-linear structure formation such as galaxy filaments and galaxy halos from the influence of dark matter. Direct ''N''-body simulations are used to study the dynamical evolution of star clusters. Nature of the particles The 'particles' treated by the simulation may or may not correspond to physical objects which are particulate in nature. For example, an N-body simulation of a star cluster might have a particle per star, so each particle has some physical significance ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
N-body Simulation
In physics and astronomy, an ''N''-body simulation is a simulation of a dynamical system of particles, usually under the influence of physical forces, such as gravity (see ''n''-body problem for other applications). ''N''-body simulations are widely used tools in astrophysics, from investigating the dynamics of few-body systems like the Earth-Moon-Sun system to understanding the evolution of the large-scale structure of the universe. In physical cosmology, ''N''-body simulations are used to study processes of non-linear structure formation such as galaxy filaments and galaxy halos from the influence of dark matter. Direct ''N''-body simulations are used to study the dynamical evolution of star clusters. Nature of the particles The 'particles' treated by the simulation may or may not correspond to physical objects which are particulate in nature. For example, an N-body simulation of a star cluster might have a particle per star, so each particle has some physical significa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
N-body Problem
In physics, the -body problem is the problem of predicting the individual motions of a group of celestial objects interacting with each other gravitationally.Leimanis and Minorsky: Our interest is with Leimanis, who first discusses some history about the -body problem, especially Ms. Kovalevskaya's 1868–1888 twenty-year complex-variables approach, failure; Section 1: "The Dynamics of Rigid Bodies and Mathematical Exterior Ballistics" (Chapter 1, "The motion of a rigid body about a fixed point (Euler and Poisson equations)"; Chapter 2, "Mathematical Exterior Ballistics"), good precursor background to the -body problem; Section 2: "Celestial Mechanics" (Chapter 1, "The Uniformization of the Three-body Problem (Restricted Three-body Problem)"; Chapter 2, "Capture in the Three-Body Problem"; Chapter 3, "Generalized -body Problem"). Solving this problem has been motivated by the desire to understand the motions of the Sun, Moon, planets, and visible stars. In the 20th century, unde ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Erik Holmberg (astronomer)
Erik Holmberg (13 November 1908 – 1 February 2000) was a Swedish astronomer and cosmologist. He is most famous for his work in the effects of interacting galaxies. This research showed that galaxies that came near each other would likely combine to form a larger galaxy. Personal life In 1908, Holmberg was born to Malcolm and Anna Holmberg in Skillingaryd, Sweden. In 1947 he married Martha Asdahl. They had one daughter named Osa, who was born in 1953. He died on 1 February 2000 in Gothenburg, at the age of 91. Scientific work In 1941, Holmberg performed arguably the first N-body simulation#Direct gravitational N-body simulations, N-body simulation on the dynamics of interacting galaxies. In order to simulate the effect, he constructed an array of 37 lightbulbs. Using photocells, he measured the simulated force of gravity. Over time, the galaxies moved closer toward each other. He also concluded in a later experiment that Elliptical galaxy, elliptical galaxies are generally older ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sverre Aarseth
Sverre Johannes Aarseth, (born 20 July 1934) is a research scientist at the Institute of Astronomy at the University of Cambridge. Although retired, Aarseth is still an active researcher. He has dedicated his career to the development of ''N''-body codes. He is the author of the NBODY family of codes, the current iteration is NBODY7. His current areas of research include the effects of stellar evolution in ''N''-body codes, the influence of black holes on stellar systems, the evolution of globular clusters, and the use of GPUs to increase the speed of his codes. Aarseth was a visiting scholar at the Institute for Advanced Study in 1986-87. He was awarded the 1998 Brouwer Award The Brouwer Award is awarded annually by the Division on Dynamical Astronomy of the American Astronomical Society for outstanding lifetime achievement in the field of dynamical astronomy. The prize is named for Dirk Brouwer. Recipients Source ... for his work on advancing dynamical astronomy. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multibody System
Multibody system is the study of the dynamic behavior of interconnected rigid or flexible bodies, each of which may undergo large translational and rotational displacements. Introduction The systematic treatment of the dynamic behavior of interconnected bodies has led to a large number of important multibody formalisms in the field of mechanics. The simplest bodies or elements of a multibody system were treated by Newton (free particle) and Euler (rigid body). Euler introduced reaction forces between bodies. Later, a series of formalisms were derived, only to mention Lagrange’s formalisms based on minimal coordinates and a second formulation that introduces constraints. Basically, the motion of bodies is described by their kinematic behavior. The dynamic behavior results from the equilibrium of applied forces and the rate of change of momentum. Nowadays, the term multibody system is related to a large number of engineering fields of research, especially in robotics and vehi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Smoothed Particle Hydrodynamics
Smoothed-particle hydrodynamics (SPH) is a computational method used for simulating the mechanics of continuum media, such as solid mechanics and fluid flows. It was developed by Gingold and Monaghan and Lucy in 1977, initially for astrophysical problems. It has been used in many fields of research, including astrophysics, ballistics, volcanology, and oceanography. It is a meshfree Lagrangian method (where the co-ordinates move with the fluid), and the resolution of the method can easily be adjusted with respect to variables such as density. Method Advantages * By construction, SPH is a meshfree method, which makes it ideally suited to simulate problems dominated by complex boundary dynamics, like free surface flows, or large boundary displacement. * The lack of a mesh significantly simplifies the model implementation and its parallelization, even for many-core architectures. * SPH can be easily extended to a wide variety of fields, and hybridized with some other model ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galaxy Filament
In cosmology, galaxy filaments (subtypes: supercluster complexes, galaxy walls, and galaxy sheets) Boris V. Komberg, Andrey V. Kravtsov, Vladimir N. Lukash; "The search and investigation of the Large Groups of Quasars" ; ;R.G. Clowes; "Large Quasar Groups - A Short Review"; ''The New Era of Wide Field Astronomy'', ASP Conference Series, vol. 232.; 2001; Astronomical Society of the Pacific; ; are the largest known structures in the universe, consisting of walls of gravitationally bound galaxy superclusters. These massive, thread-like formations can reach 80 parsec#Megaparsecs and gigaparsecs, megaparsecs ''h''−1 (or of the order of 160 to 260 million light-years) and form the boundaries between large void (astronomy), voids. Formation In the Lambda-CDM model, standard model of the evolution of the universe, galactic filaments form along and follow web-like strings of dark matter—also referred to as the galactic web or cosmic web. It is thought that this dark matter dictates ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Structure Formation
In physical cosmology, structure formation is the formation of galaxies, galaxy clusters and larger structures from small early density fluctuations. The universe, as is now known from observations of the cosmic microwave background radiation, began in a hot, dense, nearly uniform state approximately 13.8 billion years ago. However, looking at the night sky today, structures on all scales can be seen, from stars and planets to galaxies. On even larger scales, galaxy clusters and sheet-like structures of galaxies are separated by enormous voids containing few galaxies. Structure formation attempts to model how these structures were formed by gravitational instability of small early ripples in spacetime density or another emergence. The modern Lambda-CDM model is successful at predicting the observed large-scale distribution of galaxies, clusters and voids; but on the scale of individual galaxies there are many complications due to highly nonlinear processes involving baryonic phy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astronomical Calculation Institute (University Of Heidelberg)
The Astronomical Calculation Institute (german: Astronomisches Rechen-Institut; ARI) is a research institute in Heidelberg, Germany, dating from the 1700s. Beginning in 2005, the ARI became part of the Center for Astronomy at Heidelberg University (', ). Previously, the institute directly belonged to the state of Baden-Württemberg. Description The ARI has a rich history. It was founded in 1700 in Berlin-Dahlem by Gottfried Kirch. It had its origin in a patent application by Frederick I of Prussia, who introduced a monopoly on publishing star catalogs in Prussia. In 1945 the Institute was moved by the Americans nearer to the United States Army Garrison Heidelberg. On January 1, 2005 the combined Center for Astronomy institute formed by combining ARI, with the Institute of Theoretical Astrophysics (', ITA) and the Landessternwarte Heidelberg-Königstuhl ("Heidelberg-Königstuhl State Observatory", LSW). The ARI has been responsible among other things for the Gliese catal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sebastian Von Hoerner
Sebastian Rudolf Karl von Hoerner (15 April 1919 – 7 January 2003) was a German astrophysicist and radio astronomer. He was born in Görlitz, Lower Silesia. After the end of World War II he studied physics at University of Göttingen. He obtained his doctorate at the same university in 1951 as Carl Friedrich von Weizsäcker. Together they conducted simulations that studied the formation of stars and globular clusters. He continued this work at Astronomical Calculation Institute (University of Heidelberg) with Walter Fricke. He obtained his habilitation in 1959 at the University of Heidelberg. In 1962 he moved to National Radio Astronomy Observatory (Green Bank, West Virginia), where he collaborated, inter alia, with Frank Drake. He worked there, among others on the analysis of work and technical optimization of radio telescopes. His research led to the development of a new method for the construction of radio telescopes, later used in the construction of many of them. During thi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lund Observatory
Lund Observatory is the official English name for the astronomy department at Lund University. Between 1867-2001 "Lund Observatory" was also the name of the Observatory building, which is now referred to as the "Lund Old Observatory". As of January 2010, Lund Observatory is part of the Department of Astronomy and Theoretical Physics at Lund University. It is located in Lund, Sweden. History The institution was founded in 1749, but was preceded by an observatory built by astronomy professor Anders Spole (the grandfather of Anders Celsius) in 1672, which was destroyed at the Battle of Lund in 1676. The now old observatory from 1867 is located in a cultural-heritage protected observatory park just outside the medieval city boundaries. The department left these premises in 2001 for a new building on the northern campus of Lund University, inaugurated in 2001, using the nearby old water tower as their new location for astronomical observations. The history of astronomy in Lund thro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interstellar Cloud
An interstellar cloud is generally an accumulation of gas, plasma, and dust in our and other galaxies. Put differently, an interstellar cloud is a denser-than-average region of the interstellar medium, the matter and radiation that exists in the space between the star systems in a galaxy. Depending on the density, size, and temperature of a given cloud, its hydrogen can be neutral, making an H I region; ionized, or plasma making it an H II region; or molecular, which are referred to simply as molecular clouds, or sometime dense clouds. Neutral and ionized clouds are sometimes also called ''diffuse clouds''. An interstellar cloud is formed by the gas and dust particles from a red giant in its later life. Chemical compositions The chemical composition of interstellar clouds is determined by studying electromagnetic radiation that they emanate, and we receive – from radio waves through visible light, to gamma rays on the electromagnetic spectrum – that we receive from them. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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