APOD090630—北美洲星云和鹈鹕星云

http://apod.nasa.gov/apod/ap090630.html


2009 June 30
The North America and Pelican Nebulae

                               
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Credit & Copyright: Danny Lee Russell  
Explanation:
Here are some familiar shapes in unfamiliar locations. This emission nebula on the left is famous partly because it resembles Earth's continent of North America. To the right of the North America Nebula, cataloged as NGC 7000, is a less luminous nebula that resembles a pelican dubbed the Pelican Nebula. The two emission nebula measure about 50 light-years across, are located about 1,500 light-years away, and are separated by a dark absorption cloud. This spectacular image captures the nebulas, bright ionization fronts, and fine details of the dark dust. The nebulae can be seen with binoculars from a dark location. Look for a small nebular patch north-east of bright star Deneb in the constellation of Cygnus. It is still unknown which star or stars ionize the red-glowing hydrogen gas.

北京天文馆的翻译
http://www.bjp.org.cn/apod/2009-06/30/content_9384.htm

北美洲星云以及鹈鹕星云

                               
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影像提供及版权：Danny Lee Russell
说明：
这里有一些位于生疏空间里的熟悉形状。左上角的发射星云很有名，部分原因是因为它跟地球上的北美洲类似。而北美洲星云右侧是一个被编录为NGC7000的星云，比北美洲星云亮度稍差，样子看起来有些像鹈鹕，所以被称之为鹈鹕星云。两个发射星云大约有50光年宽，距离我们大约1,500光年远，中间被黑暗的吸收云隔开。这张壮观的影像捕捉到了星云，明亮的游离界面，以及黑暗尘埃较好的细节。在黑暗的地区用双筒望远镜就能看到该星云。朝天鹅座内亮星天津四的东北方就能寻找到一个小星云亮斑。现在还不知道哪颗恒星或者是哪些恒星电离了发红光的氢气。

本图APOD发过n次了，原因很简单，从它的取名就可知道了。

这是APOD大图的地址，图与北京天文馆是一样的，我就不贴了。
http://apod.nasa.gov/apod/image/0906/northpelican_russell_big.jpg

图中的主色正是H-α发射线的颜色。