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An accretion disk is a structure (often a circumstellar disk) formed by diffuse material [a] in orbital motion around a massive central body. The central body is most frequently a star . Friction , uneven irradiance, magnetohydrodynamic effects, and other forces induce instabilities causing orbiting material in the disk to spiral inward toward ...
In astrophysics, accretion is the accumulation of particles into a massive object by gravitationally attracting more matter, typically gaseous matter, into an accretion disk. [ 1 ] [ 2 ] Most astronomical objects , such as galaxies , stars , and planets , are formed by accretion processes.
The disk of a Class 0 protostar is thought to be massive and hot. It is an accretion disk, which feeds the central protostar. [39] [40] The temperature can easily exceed 400 K inside 5 AU and 1,000 K inside 1 AU. [51] The heating of the disk is primarily caused by the viscous dissipation of turbulence in it and by the infall of the gas from the ...
English: Animation showing neutron star and accretion disk evolving into a millisecond pulsar, with magnetic fields. The formation of a pulsar: A star in a binary star system has collapsed to a neutron star. It begins to gain material from its companion star (known as "accretion").
A protoplanetary disk is a rotating circumstellar disc of dense gas and dust surrounding a young newly formed star, a T Tauri star, or Herbig Ae/Be star. The protoplanetary disk may not be considered an accretion disk ; while the two are similar, an accretion disk is hotter and spins much faster; it is also found on black holes , not stars.
The brightest part of the system is the accretion disk around the compact object. The orbital periods of LMXBs range from ten minutes to hundreds of days. The variability of LMXBs are most commonly observed as X-ray bursters, but can sometimes be seen in the form of X-ray pulsars.
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The expected spectrum of an accretion disc peaks in the optical-ultraviolet waveband; in addition, a corona of hot material forms above the accretion disc and can inverse-Compton scatter photons up to X-ray energies. The radiation from the accretion disc excites cold atomic material close to the black hole and this in turn radiates at ...