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SN 185 (aka RCW 86) was a supernova which appeared in the year AD 185, near the direction of Alpha Centauri, between the constellations Circinus and Centaurus, centered at RA Dec , in Circinus. This "guest star" was observed by Chinese astronomers in the ''Book of Later Han'',〔>〕 and might have been recorded in Roman literature.〔>〕 It remained visible in the night sky for eight months. This is believed to be the first supernova for which records exist. The gaseous shell RCW 86 is probably the supernova remnant of this event and has a relatively large angular size of roughly 45 arc minutes〔>〕 (larger than the apparent size of the full moon, which varies from 29 to 34 arc minutes). The distance to RCW 86 is estimated to be .〔 Recent X-ray studies show a good match for the expected age. New infrared observations from NASA's Spitzer Space Telescope and Wide-field Infrared Survey Explorer (WISE) reveal how the supernova occurred and how its shattered remains ultimately spread out to great distances. The findings show that the stellar explosion took place in a hollowed-out cavity, allowing material expelled by the star to travel much faster and farther than it would have otherwise.〔>〕 Differing modern interpretations of the Chinese records of the guest star have led to quite different suggestions for the astronomical mechanism behind the event, from a core-collapse supernova〔 to a distant, slow-moving comet〔>〕 – with correspondingly wide-ranging estimates of its apparent visual magnitude (−8 to +4). The recent Chandra results suggest that it was most likely a Type Ia supernova (a type with consistent absolute magnitude),〔〔>〕 similar therefore to Tycho's star (which had apparent magnitude −4 at a similar distance). ==See also== * List of supernovae * History of supernova observation * List of supernova remnants * List of supernova candidates 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「SN 185」の詳細全文を読む スポンサード リンク
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