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In observational astronomy an Einstein ring, also known as an Einstein-Chwolson ring or Chwolson ring, is the deformation of the light from a source (such as a galaxy or star) into a ring through gravitational lensing of the source's light by an object with an extremely large mass (such as another galaxy or a black hole). This occurs when the source, lens, and observer are all aligned. The first complete Einstein ring, designated B1938+666, was discovered by collaboration between astronomers at the University of Manchester and NASA's Hubble Space Telescope in 1998.〔(【引用サイトリンク】 title=A Bull's Eye for MERLIN and the Hubble )〕 == Introduction == Gravitational lensing is predicted by Albert Einstein's theory of general relativity. Instead of light from a source traveling in a straight line (in three dimensions), it is bent by the presence of a massive body, which distorts spacetime. An Einstein Ring is a special case of gravitational lensing, caused by the exact alignment of the source, lens, and observer. This results in a symmetry around the lens, causing a ring-like structure. The size of an Einstein ring is given by the Einstein radius. In radians, it is : where : is the gravitational constant, : is the mass of the lens, : is the speed of light, : is the angular diameter distance to the lens, : is the angular diameter distance to the source, and : is the angular diameter distance between the lens and the source. Note that, over cosmological distances in general. 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Einstein ring」の詳細全文を読む スポンサード リンク
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