benson 2009-3-25 12:01
一個神祕的珈瑪射線爆發
GRB 060218: A Mysterious Transient
[img]http://i18.tinypic.com/2h6hsic.jpg[/img]
影像提供: SDSS Collaboration, Swift Collaboration, Sloan Foundation, NSF, NASA
[color=navy]Explanation: [/color]
[color=dimgray]What is it? Something is happening in a small portion of the sky toward the constellation of Aries. Telescopes around the globe are tracking an unusual transient there as it changes day by day. No one is sure what it will do next. The entire space mystery began on February 18 when the Earth-orbiting robot Swift satellite noticed an unusual transient began to glow dimly in gamma rays. Dubbed GRB 060218, the object is a type of gamma ray burst (GRB) but the way its brightness changes is very unusual. Since detection, GRB 060218 has been found to emit light across the electromagnetic spectrum, including radio waves and visible light. Pictured above, the Sloan Digital Sky Survey (SDSS) image of the field of GRB 060218 well prior to its Swift trigger is shown on the left, while the same field, taken by the orbiting Swift satellites' ultraviolet telescope after the Swift trigger, is shown on the right. The oddball GRB is visible in the center of the right image. Subsequent observations found a redshift for the transient of z=0.033, showing it to be only about 440 million light years away, relatively nearby compared to typical GRBs. Whether GRB 060218 represents a new type of gamma ray burst, a new type of supernova, or an unusual link between the GRBs and supernovas has become an instant topic of research. [/color]
[color=navy]說明:[/color]
[color=dimgray]這到底是什麼？有個事件發生在北天的白羊座內，只是沒人知道它到底是什麼。這個不尋常的爆發事件每日呈現不同的面貌，位在地球各地的望遠鏡也不停地追蹤它，但沒有人知道它下一步會怎麼變。這個神祕的太空事件的序幕是在2月18日，當時位在地球軌道上的快捷號衛星偵測到一個不尋常爆發，開始發出暗淡的珈瑪射線波輻射。現在名為GRB 060218的事件，它是一種珈瑪射線爆發事件，但它的亮度變化很獨特，自從被偵測到後，GRB 060218在各個電磁波段都發出輻射，包括電波波段和可見波段。上面影像的左幅是沙隆數位巡天計畫 (SDSS)在爆發前所拍攝的GRB 060218天區影像，右幅影像則是快捷號衛星被觸發後用它的紫外光望遠鏡所拍攝的。這個怪異的珈瑪射線爆發在右幅影像的中央，後續的觀測定出它的紅位移量為z=0.033，所以它的距離只有四億四千萬光年遠，算是相當近的珈瑪射線爆發事件。到底GRB 060218是種新型的珈瑪射線爆發、新型的超新星或介於珈瑪射線爆發和超新星之間的天體，已經成為科學研究的題材。 [/color]
[size=2]資料來源: Scientific American
Department of Physics, NCKU[/size][color=white][size=1]
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