The standard model for an active galactic nucleus is based upon an accretion disc that forms around a supermassive black hole ( SMBH ) at the core region.

The quasar is powered by an accretion disc around the black hole.

The matter accreting onto the black hole is unlikely to fall directly in, but will have some angular momentum around the black hole that will cause the matter to collect in an accretion disc.

However, when accretion disc energy-production mechanisms were successfully modeled in the 1970s, the argument that quasars were too luminous became moot and today the cosmological distance of quasars is accepted by almost all researchers.

In many cases, the inflowing gas forms an accretion disc around the accretor.

The result is that matter will transfer from one star to another through a process known as Roche Lobe overflow ( RLOF ), either being absorbed by direct impact or through an accretion disc.

It is not uncommon that the accretion disc is the brightest ( and thus sometimes the only visible ) element of a binary star.

In X-ray astronomy, the accretion disc surrounding a black hole is presumed to produce a thermal spectrum.

They could either be remnants from the planet's proto-planetary accretion disc that failed to coalesce into moonlets, or conversely have formed when a moon passed within its Roche limit and broke apart.

As matter spirals into a black hole, the intense gravitational gradient gives rise to intense frictional heating ; the accretion disc of a black hole is hot enough to emit X-rays just outside of the event horizon.

Angular momentum conservation prevents a straight flow from one star to the other and an accretion disc forms instead.

an accretion disc is expected to be a laminar flow.

where is the sound speed, is the disc height, and is a free parameter between zero ( no accretion ) and approximately one.

HH-30, a Herbig – Haro object surrounded by an accretion disc

When the accretion rate is sub-Eddington and the opacity very high, the standard thin accretion disc is formed.

Pringle contributed in the past thirty years many key results to accretion disc theory, and wrote the classic 1981 review that for many years was the main source of information about accretion discs, and is still very useful today.

This type of accretion disc was predicted in 1977 by Ichimaru.

* Antimatter Less exotic would be simply to capture photons already escaping from the accretion disc, reducing a black hole's angular momentum ; known as the Penrose process.

* Protoplanetary disk, a rotating disc of dense gas surrounding a newly formed star, a form of accretion disc

The infalling matter, which is usually rich in hydrogen, forms in most cases an accretion disc around the white dwarf.

Strong UV and X-ray emission is often seen from the accretion disc.

Truly, that Liberals should choose Louis 14, as a bogey-symbol of conservatism is grotesquely ironic, considering the Louis 14, character of their Grand Monarque, FDR: not only in his accretion of absolute power and personal deification, ( le roi gouverne par lui meme ), but in the disastrous effects of his spending and war policies.

A measure of the total mass accretion of meteoritic material by the Earth is obtained from analyses of deep-sea sediments and dust collected in remote regions ( Pettersson, 1960 ).

It is widely believed that giant planets form through core accretion, and that process may sometimes produce planets with masses above the deuterium fusion threshold ; massive planets of that sort may have already been observed.

There are other examples of these minor accretion events, and it is likely a continual process for many galaxies.

The observed state of gas within a cluster is determined by a combination of shock heating during accretion, radiative cooling, and thermal feedback triggered by that cooling.

The accretion rate of these water droplets is another factor in the hailstone ’ s growth.

It is caused by the accretion of hydrogen on to the surface of the star, which ignites and starts nuclear fusion in a runaway manner.

While hydrogen fusion can occur in a stable manner on the surface of the white dwarf for a narrow range of accretion rates, for most binary system parameters the hydrogen burning is thermally unstable and rapidly converts a large amount of the hydrogen into other heavier elements in a runaway reaction, liberating an enormous amount of energy, blowing the remaining gases away from the white dwarf's surface and producing an extremely bright outburst of light.

The recurrence interval for a nova is less dependent on the white dwarf's accretion rate than on its mass ; with their powerful gravity, massive white dwarfs require less accretion to fuel an outburst than lower-mass ones.

This means that it is possible that most galaxies, including our own Milky Way, have gone through an active stage ( appearing as a quasar or some other class of active galaxy depending on black hole mass and accretion rate ) and are now quiescent because they lack a supply of matter to feed into their central black holes to generate radiation.

When this accretion phase is nearly complete, the resulting object is known as a protostar.

When the surrounding gas and dust envelope disperses and accretion process stops, the star is considered a pre – main sequence star ( PMS star ).

As described above, the collapse of a rotating cloud of gas and dust leads to the formation of an accretion disk through which matter is channeled onto a central protostar.

There is mounting evidence that at least some massive protostars are indeed surrounded by accretion disks.

Of these, perhaps the most prominent is the theory of competitive accretion, which suggests that massive protostars are " seeded " by low-mass protostars which compete with other protostars to draw in matter from the entire parent molecular cloud, instead of simply from a small local region.

On astronomical scales, convection of gas and dust is thought to occur in the accretion disks of black holes, at speeds which may closely approach that of light.

Creation ( accretion ) occurs as mantle is added to the growing edges of a plate.

In particular, his research has focused on relativistic gravitation theory, the structure and behavior of accretion disks, stellar dynamics, radiative processes, and relativistic plasmas.

Temporal structure runs from “ Monday, September 8, 3: 30pm ” through “ Monday, October 13, 7: 00 a. m .; 1: 00 p. m .” Time represents the specific chronological frame of the trips, while their incremental repetition offers an accretion of being in place.

* Bruno Rossi Prize in 1988 for his contributions to understanding cosmic X-ray sources, especially the structure of accretion disks around black holes, the X-ray spectra of compact objects, and the Mir-based discovery of hard X-ray emission from supernovae 1987A

The inner structure of an Active Galaxy showing the accretion disk and relativistic jets in the vicinity of a supermassive black hole.

* Steeghs, D., Harlaftis, E. T., and Horne, K. ( 1997 ) Spiral structure in the accretion disc of IP Pegasi, Monthly Notices of the Royal Astronomical Society, 290 ( 2 ): L28 – L32.

In 1997, Goreau and I sailed to Saya de Malha's many shallow sites and established the first accretion structure there, powered by floating photovoltaics and thus claiming the banks.