FU Orionis | Article about FU Orionis by The Free Dictionary
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FU Orionis (o-rÿ -ŏ-niss, oh-, or-ee-oh -niss) A very young star, thought to be a T Tauri star, that is located in Orion in a cloud of gas and dust and is a strong source of infrared radiation. It flared up from about 16th to 10th magnitude in 1936 and has remained near that brightness. It has a high lithium content. It is the prototype of the FU Orionis stars , a group of very young stars all showing a persistent increase of several magnitudes, or thought to have recently done so.