75个邻近星系的生活方式已经在这张NASA的SPITZER空间望远镜海报上阐明了。
在这张混合图中，蓝色显示光是来自处于老年期的恒星，绿色的色彩代表一种被叫做多环芳烃的有机分子，然而红色表示被来自邻近年轻恒星辐射所加热的气体和温暖的尘埃云
星系的组成分类是靠形状，根据哈勃“音叉”
在这个构造中，椭圆星系位于海报的左边，开始产生分叉的地方。他们用E来标明，并结合使用从0到7的数字。E0星系看起来是圆的，但是E7星系却非常长和瘦
螺旋星系位于海报的右边，在产生两尖头的分叉处，最上面的尖头是由标准的螺旋星系组成，用S来标识。带状的螺旋星系组成了下面的尖头，并用SB来标记。同时，字母a b c用来表示螺旋臂的松紧程度大小，Sa星系的旋臂的螺旋程度是非常大的，但是Sc星系螺旋臂的程度就非常小。
不规则星系构成了海报的左下部，因为他们不符合最初哈勃分类法的描述。
这张海报上的星系有3种颜色混合在一起，蓝色表示星系光的波长为3.6微米,绿色的是8.0微米,红色的是24微米
The "lifestyles" of 75 neighboring galaxies are illuminated in this poster from NASA's Spitzer Space Telescope.
In this composite, blue colors reveal light from an older population of stars. Tints of green represent organic molecules called polycyclic aromatic hydrocarbons, while red lumps show clouds of warm dust and gas heated by radiation from newborn stars.
The galaxies are organized by shape, according to the Hubble-Tuning Fork.
In this structure, elliptical galaxies sit on the left side of the poster, creating the tuning fork's handle. They are designated by the letter "E", and given a number from zero to seven. An "E0" galaxy looks round, while an E7 galaxy is very long and thin.
Spiral galaxies are located to the right side of the poster creating the fork's two prongs. The top prong is made up of regular spiral galaxies, and identified by the letter "S." Barred spiral galaxies make up the bottom prong, and are branded "SB." Meanwhile, letters – "a", "b", and "c" – indicate how tightly the spiral arms are wound. An "Sa" galaxy's arms are wound very tightly, while an "Sc" galaxy's spiral arms are very loosely wound.
Irregular galaxies are organized on bottom-left side of the poster because they were not represented in Hubble's original Tuning Fork.
The galaxies in this poster are three-color composites where blue depicts the galaxies at a light wavelength of 3.6 microns, while 8.0 microns is green, and 24 microns is red.
URL：http://gallery.spitzer.caltech.e ... mage_name=sig07-025
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[ 本帖最后由 江涛 于 2008-2-21 15:02 编辑 ] |
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