charles 2009-3-23 10:37
人馬座三重星雲
Sagittarius Triplet
[img]http://i3.tinypic.com/2sbpekz.jpg[/img]
影像版權與提供: Steve Mazlin, Jim Misti
[color=navy]Explanation:[/color]
Explanation: These three bright nebulae are often featured in telescopic tours of the constellation Sagittarius and the crowded starfields of the central Milky Way. In fact, 18th century cosmic tourist Charles Messier cataloged two of them; M8, the nebula below and right of center, and colorful M20 at the upper right. The third, NGC 6559, is left of M8, separated from the the larger nebula by a dark dust lane. All three are stellar nurseries about five thousand light-years or so distant. The expansive M8, over a hundred light-years across, is also known as the Lagoon Nebula while M20's popular moniker is the Trifid. This stunning digital view is actually a collaborative composite recorded by 2 cameras and 2 telescopes about 2 thousand miles apart. The deep, wide image field was captured under dark Arizona skies. Both M8 and M20 were recorded in more detail from an observatory in Pennsylvania. Glowing hydrogen gas creates the dominant red color of the emission nebulae, with contrasting blue hues, most striking in the Trifid, due to dust reflected starlight.
[color=navy]說明:[/color]
用望遠鏡巡禮人馬座和恆星密集的銀河系中心時，這三個明亮星雲經常是目光的焦點。遠在十八世紀時梅西葉就編錄了其中二者，分別是上面影像中下方的星雲M8和位在右上角的美麗M20。第三個星雲為NGC 6559，位在M8的左方，二者被一道塵埃帶隔開。這三個星雲都是恆星誕生區，距離我們大約有五千光年遠。龐大的M8大小超過一百光年，又被稱為是礁湖星雲 (Lagoon Nebula)，而M20的著名暱稱為三裂星雲。這幅壯麗的數位影像，是由相隔三千公里的二部望遠鏡所拍攝之影像組合出來的。作為背景的深空廣角影像，拍攝的地點是美國的亞利桑那州，M8和M20的較高解所影像，則是由位在賓州的一座天文台所拍攝的。光亮的氫氣雲所發出的紅光是這些發射星雲的主要顏色，而三裂星雲內高對比性的藍色區域，則來自被雲氣所反射的星光。
[size=2]資料來源: Scientific American
Department of Physics, NCKU[/size]