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Accretion disk jets: Why do the disks surrounding certain objects, such as the nuclei of active galaxies, emit jets along their polar axes? These jets are invoked by astronomers to do everything from getting rid of angular momentum in a forming star to reionizing the universe (in active galactic nuclei), but their origin is still not well understood.
Accretion disks are also commonly present in the centre of galaxies, and in some cases can be extremely luminous: quasars, for example, are thought to originate from a gaseous disk surrounding a very massive black hole. Our modern understanding of the MRI arose from attempts to understand the behavior of accretion disks in the presence of ...
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.
In astronomy, a disk wind is a particle outflow observed around accretion disks, mainly near protoplanetary disks [1] [2] and active galactic nulei (AGN). [3] [4] The disk wind is made up of a gaseous and a dusty component. [1] Especially in edge-on protoplanetary disks this disk wind can be directly imaged. [5] [6]
The double-burst variability is thought to result from the smaller black hole punching through the accretion disc of the larger black hole twice in every 12 years. [5] A secondary black hole orbits the larger one with an observed orbital period of approximately 12 years and a calculated eccentricity of approximately 0.65. [4]
The star, growing and accreting material from the surrounding disk, is about 10 to 20 times more massive than the sun and perhaps 10,000 times more luminous. In a first, a newborn star's spinning ...
This material often forms an accretion disk. Similar luminous accretion disks can also form around white dwarfs and neutron stars, but in these the infalling gas releases additional energy as it slams against the high-density surface with high speed. In case of a neutron star, the infall speed can be a sizeable fraction of the speed of light.
They likely arise from dynamic interactions within accretion disks, whose active processes are commonly connected with compact central objects such as black holes, neutron stars or pulsars. One explanation is that tangled magnetic fields are organised to aim two diametrically opposing beams away from the central source by angles only several ...