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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 ...
About 6% of white dwarfs show infrared excess due to a disk around a white dwarf. [66] In the past only a relative small sample of white dwarf disks was known. [67] Due to advances in white dwarf detection (e.g. with Gaia or LAMOST) and improvement of WISE infrared catalogs with unWISE/CatWISE, the number has increased to hundreds of candidates.
[1] [2] Until 2021 it was the oldest and coldest white dwarf known to host a disk. The white dwarf WD 2317+1830 with a detected disk is at least twice as old and around 2,000 K colder. [3] [4] The white dwarf has a radius of 0.011 R ☉, which is about 1.2 times the radius of the earth. Because white dwarfs are such dense objects, LSPM J0207 ...
In 2018, detailed observations by X-ray and ultraviolet telescopes revealed that the AGN's accretion disk had undergone a partial or total disruption. [14] The Quasi-periodic oscillation (QPO) period shrank from 18 to 7.1 minutes over two years, showing unique evolution. [ 16 ]
The researchers also detected infrared excess, indicative of a debris disk, around this white dwarf. The disk is inclined by 70°, has an inner disk temperature of 1,500 K and an outer disk temperature of 500 K. In the past WD 2317+1830 had a mass of 4.8 ± 0.2 M ☉ and was likely a B-type star. [3]
2MASS J11151597+1937266 (also called 2MASS J1115+1937) is a young isolated planetary-mass object that is surrounded by a planetary disk. [4] [1] [3]2MASS J1115+1937 was discovered in 2017 in the LaTE-MoVeRS survey (Late-Type Extension to the Motion Verified Red Stars), which combined 2MASS, SDSS and WISE data to search for faint moving stars.
First solitary white dwarf Van Maanen 2: 1917 Van Maanen's star is also the nearest solitary white dwarf [5] First white dwarf with a planet WD B1620−26: 2003 PSR B1620-26 b (planet) This planet is a circumbinary planet, which circles both stars in the PSR B1620-26 system [6] [7] First singular white dwarf with a transiting object WD 1145+017 ...
The material from an accreted asteroid will first form a disk around the white dwarf. Closer to the white dwarf the dusty material will sublimate into a metal-gas. The researchers claim that white dwarf will ionize at least a part of the gas. These ions will follow the magnetic field of the white dwarf and as a result of the Lorentz force it ...