oscar 2009-3-21 09:57
NGC 1499: 加州星雲
NGC 1499: The California Nebula
[img]http://i11.tinypic.com/3y4axcz.jpg[/img]
影像提供: Caltech, Palomar Observatory, Digitized Sky Survey; Courtesy: Scott Kardel
[color=navy]Explanation: [/color]
What's California doing in space? Drifting through the Orion Arm of the spiral Milky Way Galaxy, this cosmic cloud by chance echoes the outline of California on the west coast of the United States. Our own Sun also lies within the Milky Way's Orion Arm, only about 1,500 light-years from the California Nebula. Also known as NGC 1499, the classic emission nebula is around 100 light-years long. It glows with the red light characteristic of hydrogen atoms recombining with long lost electrons, stripped away (ionized) by energetic starlight. In this case, the star most likely providing the energetic starlight is the bright, hot, bluish Xi Persei, just right of the nebula and above picture center. Fittingly, this composite picture was made with images from a telescope in California - the 48-inch (1.2-meter) Samuel Oschin Telescope - taken as a part of the second National Geographic Palomar Observatory Sky Survey.
[color=navy]說明: [/color]
加州為何會在太空中？在銀河系獵戶臂內漂流的這朵宇宙雲，形狀恰好和美國西岸的加州外觀相似，所以得到加州星雲 (California Nebula)的雅號。 我們的太陽也位在銀河系的獵戶臂內，和加州星雲的距離大約是一千五百光年。這個典型的發射星雲又稱為NGC 1499，長度大約有一百光年。 星雲紅色特徵輝光是氫原子被高能量星光剝去(游離)一個電子之後，氫再得回失去的電子時所輻射出來的光。 在上面這個例子裡，射出這些高能量星光的恆星，很可能是位在星雲右側上方的明亮熾熱藍色英仙座Xi星 (Xi Persei)。 很恰當地，提供影像組合出這張照片的是位在加州的1.2米Samuel Oschin望遠鏡，這批影像是第二次國家地理雜誌-帕洛瑪天文台巡天計畫的一部份。
[size=2]資料來源: Scientific American
Department of Physics, NCKU[/size]