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Accretion disk

Index Accretion disk

An accretion disk is a structure (often a circumstellar disk) formed by diffused material in orbital motion around a massive central body. [1]

64 relations: Accretion (astrophysics), Active galactic nucleus, Advection, Angular momentum, Angular velocity, Astrophysical jet, Binary system, Black hole, Blandford–Znajek process, Bohdan Paczyński, Circumstellar disc, Dynamo theory, Eddington luminosity, Eddy (fluid dynamics), Electrical resistivity and conductivity, Electromagnetic radiation, Electromagnetic spectrum, Event horizon, Fluid dynamics, Formation and evolution of the Solar System, Friction, Full width at half maximum, Gamma-ray burst, Gravitational lens, Gravitational singularity, Herbig Ae/Be star, Hydrostatic equilibrium, Infrared, Interstellar medium, Laminar flow, Luminosity, Magnetic diffusivity, Magnetic flux, Magnetorotational instability, Mass, Molecular cloud, NASA, Neutron star, Nikolai Shakura, Nuclear fusion, NuSTAR, Orbit, Planetary system, Primary (astronomy), Protoplanetary disk, Protostar, Quasar, Quasi-periodic oscillation, Rashid Sunyaev, Ring system, ..., Rings of Saturn, Roche lobe, Shakura, Speed of sound, Spin-flip, Star, T Tauri star, Tendex line, Toroidal and poloidal, Torus, Turbulence, Viscosity, White dwarf, X-ray. Expand index (14 more) »

Accretion (astrophysics)

In astrophysics, accretion is the accumulation of particles into a massive object by gravitationally attracting more matter, typically gaseous matter, in an accretion disk.

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Active galactic nucleus

An active galactic nucleus (AGN) is a compact region at the center of a galaxy that has a much higher than normal luminosity over at least some portion—and possibly all—of the electromagnetic spectrum, with characteristics indicating that the excess luminosity is not produced by stars.

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Advection

In the field of physics, engineering, and earth sciences, advection is the transport of a substance by bulk motion.

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Angular momentum

In physics, angular momentum (rarely, moment of momentum or rotational momentum) is the rotational equivalent of linear momentum.

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Angular velocity

In physics, the angular velocity of a particle is the rate at which it rotates around a chosen center point: that is, the time rate of change of its angular displacement relative to the origin.

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Astrophysical jet

An astrophysical jet is an astronomical phenomenon where outflows of ionised matter are emitted as an extended beam along the axis of rotation.

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Binary system

A binary system is a system of two astronomical bodies which are close enough that their gravitational attraction causes them to orbit each other around a barycenter (also see animated examples).

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Black hole

A black hole is a region of spacetime exhibiting such strong gravitational effects that nothing—not even particles and electromagnetic radiation such as light—can escape from inside it.

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Blandford–Znajek process

The Blandford–Znajek process is a mechanism for the extraction of energy from a rotating black hole, introduced by Roger Blandford and Roman Znajek in 1977.

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Bohdan Paczyński

Bohdan Paczyński or Bohdan Paczynski (8 February 1940 – 19 April 2007) was a Polish astronomer notable in the theory of the stellar evolution, accretion discs, and gamma ray bursts.

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Circumstellar disc

A circumstellar disc (or circumstellar disk) is a torus, pancake or ring-shaped accumulation of matter composed of gas, dust, planetesimals, asteroids or collision fragments in orbit around a star.

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Dynamo theory

In physics, the dynamo theory proposes a mechanism by which a celestial body such as Earth or a star generates a magnetic field.

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Eddington luminosity

The Eddington luminosity, also referred to as the Eddington limit, is the maximum luminosity a body (such as a star) can achieve when there is balance between the force of radiation acting outward and the gravitational force acting inward.

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Eddy (fluid dynamics)

In fluid dynamics, an eddy is the swirling of a fluid and the reverse current created when the fluid is in a turbulent flow regime.

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Electrical resistivity and conductivity

Electrical resistivity (also known as resistivity, specific electrical resistance, or volume resistivity) is a fundamental property that quantifies how strongly a given material opposes the flow of electric current.

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Electromagnetic radiation

In physics, electromagnetic radiation (EM radiation or EMR) refers to the waves (or their quanta, photons) of the electromagnetic field, propagating (radiating) through space-time, carrying electromagnetic radiant energy.

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Electromagnetic spectrum

The electromagnetic spectrum is the range of frequencies (the spectrum) of electromagnetic radiation and their respective wavelengths and photon energies.

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Event horizon

In general relativity, an event horizon is a region in spacetime beyond which events cannot affect an outside observer.

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Fluid dynamics

In physics and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids - liquids and gases.

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Formation and evolution of the Solar System

The formation and evolution of the Solar System began 4.6 billion years ago with the gravitational collapse of a small part of a giant molecular cloud.

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Friction

Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other.

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Full width at half maximum

Full width at half maximum (FWHM) is an expression of the extent of function given by the difference between the two extreme values of the independent variable at which the dependent variable is equal to half of its maximum value.

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Gamma-ray burst

In gamma-ray astronomy, gamma-ray bursts (GRBs) are extremely energetic explosions that have been observed in distant galaxies.

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Gravitational lens

A gravitational lens is a distribution of matter (such as a cluster of galaxies) between a distant light source and an observer, that is capable of bending the light from the source as the light travels towards the observer.

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Gravitational singularity

A gravitational singularity or spacetime singularity is a location in spacetime where the gravitational field of a celestial body becomes infinite in a way that does not depend on the coordinate system.

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Herbig Ae/Be star

A Herbig Ae/Be star (HAeBe) is a pre-main-sequence star – a young (V. Mannings & A. Sargent (2000) High-resolution studies of gas and dust around young intermediate-mass stars: II. observations of an additional sample of Herbig Ae/Be systems. Astrophysical Journal, vol. 529, p. 391 Hydrogen and calcium emission lines are observed in their spectra. They are 2-8 Solar mass objects, still existing in the star formation (gravitational contraction) stage and approaching the main sequence (i.e. they are not burning hydrogen in their center). In the Hertzsprung–Russell diagram these stars are located to the right of the main sequence. They are named after the American astronomer George Herbig, who first distinguished them from other stars in 1960. The original Herbig criteria were.

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Hydrostatic equilibrium

In fluid mechanics, a fluid is said to be in hydrostatic equilibrium or hydrostatic balance when it is at rest, or when the flow velocity at each point is constant over time.

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Infrared

Infrared radiation (IR) is electromagnetic radiation (EMR) with longer wavelengths than those of visible light, and is therefore generally invisible to the human eye (although IR at wavelengths up to 1050 nm from specially pulsed lasers can be seen by humans under certain conditions). It is sometimes called infrared light.

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Interstellar medium

In astronomy, the interstellar medium (ISM) is the matter and radiation that exists in the space between the star systems in a galaxy.

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Laminar flow

In fluid dynamics, laminar flow (or streamline flow) occurs when a fluid flows in parallel layers, with no disruption between the layers.

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Luminosity

In astronomy, luminosity is the total amount of energy emitted per unit of time by a star, galaxy, or other astronomical object.

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Magnetic diffusivity

The magnetic diffusivity is a parameter in plasma physics which appears in the magnetic Reynolds number.

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Magnetic flux

In physics, specifically electromagnetism, the magnetic flux (often denoted or) through a surface is the surface integral of the normal component of the magnetic field B passing through that surface.

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Magnetorotational instability

The magnetorotational instability or MRI is a fluid instability that causes an accretion disk orbiting a massive central object to become turbulent.

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Mass

Mass is both a property of a physical body and a measure of its resistance to acceleration (a change in its state of motion) when a net force is applied.

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Molecular cloud

A molecular cloud, sometimes called a stellar nursery (if star formation is occurring within), is a type of interstellar cloud, the density and size of which permit the formation of molecules, most commonly molecular hydrogen (H2).

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NASA

The National Aeronautics and Space Administration (NASA) is an independent agency of the executive branch of the United States federal government responsible for the civilian space program, as well as aeronautics and aerospace research.

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Neutron star

A neutron star is the collapsed core of a large star which before collapse had a total of between 10 and 29 solar masses.

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Nikolai Shakura

Nikolai Ivanovich Shakura (Николай Иванович Шакура; born October 7, 1945 in Belarus SSR) is a Russian astrophysicist.

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Nuclear fusion

In nuclear physics, nuclear fusion is a reaction in which two or more atomic nuclei come close enough to form one or more different atomic nuclei and subatomic particles (neutrons or protons).

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NuSTAR

NuSTAR (Nuclear Spectroscopic Telescope Array) is a space-based X-ray telescope that uses a conical approximation to a Wolter telescope to focus high energy X-rays from astrophysical sources, especially for nuclear spectroscopy, and operates in the range of 3 to 79 keV.

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Orbit

In physics, an orbit is the gravitationally curved trajectory of an object, such as the trajectory of a planet around a star or a natural satellite around a planet.

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Planetary system

A planetary system is a set of gravitationally bound non-stellar objects in or out of orbit around a star or star system.

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Primary (astronomy)

A primary (also called a gravitational primary, primary body, or central body) is the main physical body of a gravitationally bound, multi-object system.

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Protoplanetary disk

A protoplanetary disk is a rotating circumstellar disk of dense gas and dust surrounding a young newly formed star, a T Tauri star, or Herbig Ae/Be star.

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Protostar

A protostar is a very young star that is still gathering mass from its parent molecular cloud.

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Quasar

A quasar (also known as a QSO or quasi-stellar object) is an extremely luminous active galactic nucleus (AGN).

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Quasi-periodic oscillation

In X-ray astronomy, quasi-periodic oscillation (QPO) is the manner in which the X-ray light from an astronomical object flickers about certain frequencies.

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Rashid Sunyaev

Rashid Alievich Sunyaev (Рәшит Гали улы Сөнәев, Раши́д Али́евич Сюня́ев; born 1 March 1943 in Tashkent, USSR) is a Soviet and Russian astrophysicist of Tatar descent.

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Ring system

A ring system is a disc or ring orbiting an astronomical object that is composed of solid material such as dust and moonlets, and is a common component of satellite systems around giant planets.

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Rings of Saturn

The rings of Saturn are the most extensive ring system of any planet in the Solar System.

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Roche lobe

The Roche lobe (or Roche limit) is the region around a star in a binary system within which orbiting material is gravitationally bound to that star.

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Shakura

Shakura (Шаку́ра) may refer to:; Family name.

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Speed of sound

The speed of sound is the distance travelled per unit time by a sound wave as it propagates through an elastic medium.

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Spin-flip

A black hole spin-flip occurs when the spin axis of a rotating black hole undergoes a sudden change in orientation due to absorption of a second (smaller) black hole.

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Star

A star is type of astronomical object consisting of a luminous spheroid of plasma held together by its own gravity.

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T Tauri star

T Tauri stars (TTS) are a class of variable stars associated with youth.

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Tendex line

A tendex line (from the Latin "tendere": To stretch) is a traversal line describing the path matter takes through the accretion disc of a black hole.

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Toroidal and poloidal

The earliest use of these terms cited by the Oxford English Dictionary (OED) is by Walter M. Elsasser (1946) in the context of the generation of the Earth's magnetic field by currents in the core, with "toroidal" being parallel to lines of latitude and "poloidal" being in the direction of the magnetic field (i.e. towards the poles).

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Torus

In geometry, a torus (plural tori) is a surface of revolution generated by revolving a circle in three-dimensional space about an axis coplanar with the circle.

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Turbulence

In fluid dynamics, turbulence or turbulent flow is any pattern of fluid motion characterized by chaotic changes in pressure and flow velocity.

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Viscosity

The viscosity of a fluid is the measure of its resistance to gradual deformation by shear stress or tensile stress.

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White dwarf

A white dwarf, also called a degenerate dwarf, is a stellar core remnant composed mostly of electron-degenerate matter.

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X-ray

X-rays make up X-radiation, a form of electromagnetic radiation.

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Accretion Disc, Accretion Disk, Accretion disc, Accretion disks, Accretion theory, Advection Dominated Accretion Flow, Advection-dominated accretion flow, Disko seismology, Disko-seismology, Diskoseismology, Excretion disc, Excretion disk.

References

[1] https://en.wikipedia.org/wiki/Accretion_disk

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