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SGR J1550-5418 is a soft gamma repeater (SGR), the sixth to be discovered, located in the constellation Norma. Long known as an X-ray source, it was noticed to have become active on 23 October 2008, and then after a relatively quiescent interval, became much more active on 22 January 2009. It has been observed by the Swift satellite, and by the Fermi Gamma-ray Space Telescope, launched in 2008, as well as in X-ray and radio emission. 〔(SpaceRef news item, 10 February 2009. )〕〔(NASA press release from GSFC )〕 It has been observed to emit intense bursts of gamma rays at a rate of up to several per minute. At its estimated distance of 30,000 light years (~10 kpc), the most intense flares equal the total energy emission of the Sun in ~20 years. The underlying object is believed to be a rotating neutron star, of the type known as ''magnetars'', which have magnetic fields up to 1015 gauss, about 1000 times that of more typical neutron star X-ray sources. See Orders of magnitude (magnetic field) for examples of other magnetic field strengths. The rotation period, ~2.07 s, is the fastest yet observed for a magnetar.〔 The first observation of "Light echos" from a gamma-ray source, a phenomenon long known for visible stars such as novas, have been observed from SGR J1550-5418. The location of SGR J1550-5418 (aka AXP 1E 1547.0-5408),〔(GCN CIRCULAR 8901 )〕 is RA(J2000) = 15h50m54.11s, Dec(J2000) = -54°18´23.7´´.〔(SGR/AXP Online Catalog ) (An online catalog of AXP properties maintained by the pulsar group at McGill University)〕 == References == 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「SGR J1550-5418」の詳細全文を読む スポンサード リンク
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