Edge-On Galaxy NGC 5866
影像提供: NASA, ESA, and The Hubble Heritage Team (STScI/AURA); Acknowledgment: W. Keel (U. Alabama)
Explanation:
Why is this galaxy so thin? Many disk galaxies are actually just as thin as NGC 5866, pictured above, but are not seen edge-on from our vantage point. One galaxy that is situated edge-on is our own Milky Way Galaxy. Classified as a lenticular galaxy, NGC 5866 has numerous and complex dust lanes appearing dark and red, while many of the bright stars in the disk give it a more blue underlying hue. The blue disk of young stars can be seen extending past the dust in the extremely thin galactic plane, while the bulge in the disk center appears tinged more orange from the older and redder stars that likely exist there. Although similar in mass to our Milky Way Galaxy, light takes about 60,000 years to cross NGC 5866, about 30 percent less than light takes to cross our own Galaxy. In general, many disk galaxies are very thin because the gas that formed them collided with itself as it rotated about the gravitational center. Galaxy NGC 5866 lies about 44 million light years distant toward the constellation of the Dragon (Draco).
說明:
這個星系為何這麼薄？許多扁平盤星系其實和上面影像中NGC 5866的一樣薄，只不過我們不是剛好側視它們而已。我們在地球上所側視的星系也包括我們的銀河系。被歸類為透鏡狀星系的NGC 5866，有難以數計黝黑或暗紅的複雜塵埃帶，而盤面上的眾多亮星，讓星系帶著偏藍的底色。年輕恆星所構成的藍色星盤，延伸的範圍超過極細窄星系盤上的塵埃帶，盤面中心的星系核心可能在該處較老較紅恆星的渲染下，帶有橘紅色的色澤。雖然在外觀上NGC 5866和我們的銀河系相似，但光只要用上六萬年就能橫過它，所以它的大小比銀河系要小上百分之三十。基本上許多星系會很細窄，是因為組成這些星系的雲氣在繞重力中心旋轉時會互相衝撞。星系NGC 5866位在天龍座內，離我們約有4千4百萬光年遠。
資料來源: Scientific American
Department of Physics, NCKU
