Astronomy Picture of the Day

Explanation: This strangely distorted galaxy of stars is cataloged as NGC 4650A. It lies about 165 million light-years away in the southern constellation Centaurus. The complex system seems to have at least two parts, a flattened disk of stars with a dense, bright, central core and a sparse, sharply tilted ring of gas, dust and stars. Observations show that the stars in the disk and the stars and gas in the ring really do move in two different, nearly perpendicular planes, probably as the result of a past galaxy vs. galaxy collision. The observed motions within both disk and ring also indicate the presence of "dark matter" - an unseen source of gravity which influences the movement of this system's visible stars. Over the decades evidence that our Universe is largely composed of such dark matter has grown while the nature of dark matter has remained a profound astrophysical mystery. The picture was constructed from images made using part of the European Southern Observatory's (ESO) new Very Large Telescope system now undergoing its testing phase.

這個奇怪的扭曲星系之編錄號為NGC 4650A。 它位於南天半人馬座方向大約1.65億光年遠之處。 這個複雜的系統似乎至少有兩個部分，一是扁平的恒星盤，另一是緻密、明亮的中央核心及稀疏大角度傾斜的氣體、塵埃和恒星環。 觀測證實，盤內的恒星和環內的恒星和氣體，分別在兩個不同、幾乎垂直的平面上運動，而這可能是星系過去發生星系互撞的結果。 所觀測到的盤和環內的運動，也隱指 "暗物質 "這種不可見重力源的存在，它以重力影響這個系統可見恒星的運動。 數十年來，有越來越多證據支持我們的宇宙主要是由這種暗物質組成的，然而暗物質的性質，仍然是一個深奧的天體物理學之謎。 這張照片部分是由歐南天文臺（ESO）新上線的極大望遠鏡系統之部分影像建構而成的，該系統目前正處於測試階段。