oscar 2009-3-21 09:57
漩渦星系 NGC 5905 以及 5908
[img]http://i13.tinypic.com/2q0kf2x.jpg[/img]
Credit & Copyright: Stefan Seip
[color=navy]Explanation: [/color]
These two beautiful galaxies, NGC 5905 (left) and NGC 5908 lie about 140 million light-years distant in the northern constellation Draco. Separated by about 500,000 light-years, the pair are actually both spiral galaxies and nicely illustrate the striking contrasts in appearance possible when viewing spirals from different perspectives. Seen face-on, NGC 5905 is clearly a spiral galaxy with bright star clusters tracing arms that wind outward from a prominent central bar. Oriented edge-on to our view, the spiral nature of NGC 5908 is revealed by a bright nucleus and dark band of obscuring dust characteristic of a spiral galaxy's disk. In fact, NGC 5908 is similar in appearance to the well studied edge-on spiral galaxy M104 - The Sombrero Galaxy.
[color=navy]說明: [/color]
這兩個漂亮的星系，左邊是 NGC 5905，右邊是 NGC 5908，距離我們一億四千萬光年，位於北天的星座 天龍座(Draco)內。 兩個星系距離約五十萬光年，這一對星系是 漩渦星系(spiralgalaxies)。並且可以用來說明當我們看漩渦星系，以不同的角度來看。 從正面(face-on)來看， NGC 5905確實是一個由星團所構成懸臂的星系，懸臂是由 星系中心棒吹出的風所形成。 從側面來看，NGC 5908可以看出很亮的星系核以及塵埃所組成的暗帶，這也是漩渦狀星系盤面的特徵。 事實上，NGC 5908很類似被廣泛研究的側面漩渦狀星系M104，又稱為 草帽銀河(Sombrero Galaxy) 。
[size=2]資料來源: Scientific American
Department of Physics, NCKU[/size]