accretion disk


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Related to accretion disk: black hole, event horizon

accretion disk

See black hole; mass transfer; quasar.

accretion disk

[ə′krē·shən ‚disk]
(astronomy)
A viscous structure consisting of gas lost by a red giant or supergiant flowing around a companion main-sequence star or compact object (white dwarf, neutron star, or black hole).
References in periodicals archive ?
For example, the nearest massive protostar, a future B-type star known as Orion Source I, sports an X-shaped wind flowing off its accretion disk. (Go to http://is.gd/ massivestars to watch this wind flow in a movie made from two years of observations.) Astronomers have also spotted narrower jets emitted from more than a dozen massive protostars.
Astronomers predicted that when the X-ray source near the black hole flared, the broad iron K line would brighten after a delay corresponding to how long the X-rays took to reach and illuminate the accretion disk. Astronomers call the process relativistic reverberation.
"The idea that the accretion disk blocks our view of the central neutron star must be wrong," says Michael R.
"The central accretion disk can warp as it spirals in toward the black hole, under the influence of the black hole's spin," Douglas Finkbeiner, co-author of the study, said.
As gas spirals closer and closer to the black hole in a structure called an accretion disk, this material gets heated to extremely high temperatures and gives off high-energy radiation," NASA said in a (https://www.nasa.gov/feature/jpl/andromedas-bright-x-ray-mystery-solved-by-nustar) statement released Thursday.
The key is in looking at the size of the gap between the black hole's accretion disk and a larger ring of dust that lies around it.
The flowing gas forms a flattened accretion disk millions of miles across, several times wider than our sun, centered on the black hole.
This infalling matter--interstellar gas and disrupted stars--gathers in an accretion disk around the black hole.
This avalanche itself may have been triggered by a larger-than-usual clump of debris being drawn into the star's accretion disk.
Observers estimate spin using X-rays, which many think are produced by a hot corona above and below the accretion disk. These X-rays reflect off the innermost disk, where spacetime is warped and dragged around by the spinning black hole.
This theory proposes that the quasiperiodic pulses represent a "beat" frequency, a combination of the precise rotations of the neutron star with the variable rotations of an accretion disk around it.
Read: (http://www.ibtimes.com/scientists-create-better-model-simulate-accretion-disk-flow-around-milky-ways-2465752) Scientists Simulate Accretion Disk Flow Around Sagittarius A*