車輪星系
Cartwheel of Fortune <br />
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<img src="http://i18.tinypic.com/3zu563t.jpg" border="0" onclick="zoom(this)" onload="attachimg(this, 'load')" alt="" /><br />
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影像提供: Chandra, GALEX, Hubble, Spitzer - Composite: NASA/JPL/Caltech/P.Appleton et al. <br />
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<font color="navy">Explanation: </font><br />
<font color="dimgray">By chance, a collision of two galaxies has created a surprisingly recognizable shape on a cosmic scale - The Cartwheel Galaxy. The Cartwheel is part of a group of galaxies about 400 million light years away in the constellation Sculptor (two smaller galaxies in the group are visible below and left). Its rim is an immense ring-like structure over 100,000 light years in diameter, composed of star forming regions filled with extremely bright, massive stars. When galaxies collide they pass through each other, their individual stars do not come into contact. However, this ring-like shape is the result of gravitational disruption caused by a smaller galaxy passing through a large one, compressing the interstellar gas and dust and causing a star formation wave to move out like a ripple across the surface of a pond. This false-color composite image of the Cartwheel Galaxy is from space-based observatories. The Chandra X-ray Observatory data is in purple, the Galaxy Evolution Explorer ultraviolet view is in blue, the Hubble Space Telescope visible light picture is in green and the Spitzer Space Telescope infrared image is in red. </font><br />
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<font color="navy">說明:</font><br />
<font color="dimgray">在意外之下，二個星系互撞造出了一個日常物品的宇宙級樣品--車輪星系。車輪星系位在玉夫座 (Sculptor)內，是離我們四百萬光年遠一個星系團的成員之一。影像中也可以見到星系團另外的二個成員他，它們位在車輪星系的左下方。車輪星系由恆星形成區的輪圈直徑超十萬光年，醒面有許多極端明亮的大質量恆星。當星系互撞時它們穿過對方，所屬的個別恆星並不會互撞。不過，當較小的星系穿過較大星系時，重力的擾動壓縮恆際介質和塵埃雲氣，引出一波向外傳播的恆星誕生波，如同傳過水溏的水波，造出這種環狀結構。這張車輪星系的假色影像是由數張太空照片組合出來的，其中紫色是來自錢卓拉X射線觀測站的數據、星系演化探索衛星的紫外光影像是藍色、哈伯太空望遠鏡的可見光影像是綠色、而史匹哲太空望遠鏡的紅外影像則是紅色。</font><br />
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<font size="2">資料來源: Scientific American<br />
Department of Physics, NCKU</font><font color="white"><font size="1"><br />
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