M51: The Whirlpool Galaxy in Dust and Stars
影像提供: N. Scoville (Caltech), T. Rector (U. Alaska, NOAO) et al., Hubble Heritage Team, NASA
Explanation:
The Whirlpool Galaxy is a classic spiral galaxy. At only 30 million light years distant and fully 60 thousand light years across, M51, also known as NGC 5194, is one of the brightest and most picturesque galaxies on the sky. The above image is a digital combination of a ground-based image from the 0.9-meter telescope at Kitt Peak National Observatory and a space-based image from the Hubble Space Telescope highlighting sharp features normally too red to be seen. Anyone with a good pair of binoculars, however, can see this Whirlpool toward the constellation of Canes Venatici. M51 is a spiral galaxy of type Sc and is the dominant member of a whole group of galaxies. Astronomers speculate that M51's spiral structure is primarily due to its gravitational interaction with a smaller galaxy just off the top of this digitally sharpened image.
說明:
距離我們三千萬光年遠，大小有六萬年的渦狀星系M51又稱為NGC 5194，它是一個很典型的螺旋星系，也是夜空中最明亮且最上鏡頭的星系之一。 上面這張影像，是由美國基特峰國家天文臺(KPNO)90公分口徑的望遠鏡照片以及哈伯望遠鏡影像組合出來的，目的是要強調通常是太偏紅所以地面不可見的M51結構。 不過任何擁有一具雙筒望遠鏡的觀星人，都應該能在北天的獵犬座 (Canes Venaciti)看到這個渦狀的美麗星系。 M51被歸類成Sc型的螺旋星系，它是M51所屬的星系團裡最顯眼的星系。 天文學家懷疑M51的螺旋結構，是它和位在影像頂端外的較小型星系重力作用下的產物。
資料來源: Scientific American
Department of Physics, NCKU
