charles 2009-3-23 10:28
星雲NGC 6888及周圍的星場
NGC 6888: A Tricolor Starfield
[img]http://i14.tinypic.com/2h7dnhv.jpg[/img]
影像版權與提供: Don Goldman
[color=navy]Explanation:[/color]
NGC 6888, also known as the Crescent Nebula, is a cosmic bubble about 25 light-years across, blown by winds from its central, bright, massive star. Near the center of this intriguing widefield view of interstellar gas clouds and rich star fields of the constellation Cygnus, NGC 6888 is about 5,000 light-years away. The three color composite image was created by stacking exposures through narrow band filters that transmit the light from atoms in the clouds. Hydrogen is shown as green, sulfur as red, and oxygen as blue. NGC 6888's central star is classified as a Wolf-Rayet star (WR 136) and is shedding its outer envelope in a strong stellar wind, ejecting the equivalent of our Sun's mass every 10,000 years. Burning fuel at a prodigious rate and near the end of its stellar life, this star should ultimately go out with a bang in a spectacular supernova explosion.
[color=navy]說明:[/color]
NGC 6888又名為眉月星雲 (Crescent Nebula)，它是一個直徑約有25光年的宇宙泡泡，是由位在它中心的大質量亮星之恆星風所造成的。在上面這幅天鵝座星雲與富星場的有趣廣角影像裡，NGC 6888位在影像的中央，距離我們約有五千光年遠。這幅三色合成的彩色影像，是用只透過星雲某些特定原子所發出的光之窄波段濾鏡影像疊加出來的；其中，氫原子的光以綠色呈現，硫為紅色，而氧則為藍色。NGC 6888的中心星被歸類為沃夫-瑞葉型恆星 (WR 136)，它透過強烈的恆星風拋出它的外層氣殼，每一萬年累積拋擲出和我們太陽相當的質量。這顆恆星以不可思議的速率燃繞燃料，並且已接近恆星生命的末期，它將會以超新星爆炸的形式謝幕。
[size=2]資料來源: Scientific American
Department of Physics, NCKU[/size]