charles 2009-3-23 10:39
NGC 6164: 雙極狀的發射星雲
NGC 6164: A Bipolar Emission Nebula
[img]http://i11.tinypic.com/4cb1q0y.jpg[/img]
影像版權與提供: Gemini Obs., AURA, NSF
[color=navy]Explanation:[/color]
How did a star form this beautiful nebula? In the middle of emission nebula NGC 6164-5 is an unusually massive star nearing the end of its life. The star, visible in the center of the above image and catalogued as HD 148937, is so hot that the ultraviolet light it emits heats up gas that surrounds it. That gas was likely thrown off from the star, possibly by its fast rotation, like a rotating lawn sprinkler. Expelled material might have been further channeled by the magnetic field of the star, creating the symmetric shape of the bipolar nebula. Several cometary knots of gas are also visible on the lower left. NGC 6164-5 spans about four light years and is located about 4,000 light years away toward the southern constellation Norma.
[color=navy]說明:[/color]
恆星如何製造出這個美麗的星雲？NGC 6164-5這團發射星雲的中心，有顆接近生命末期的不尋常大質量恆星。這顆位在上面影像中央、編號為HD 148937的恆星是如此熾熱，以至於它發出的紫外輻射加熱了周圍的雲氣。因為這顆恆星自轉很快速，因此這些雲氣可能被拋擲出來的，情形類似草坪旋轉灑水器會噴灑水一樣。被拋出的物質進一步受到恆星磁場之引導，產生了對稱的雙極狀星雲。此外，在影像的左下端也可以見到數個彗星狀的物質糾結。NGC 6164-5位在南天的圓規座內，距離我們約有4,000光年遠鄉，大小有四光年。
[size=2]資料來源: Scientific American
Department of Physics, NCKU[/size]