Infrared Andromeda
影像版權與提供: Pauline Barmby (Harvard-Smithsonian CfA) et al., JPL, Caltech, NASA
Explanation:
This wide, detailed Spitzer Space Telescope view features infrared light from dust (red) and old stars (blue) in Andromeda, a massive spiral galaxy a mere 2.5 million light-years away. In fact, with over twice the diameter of our own Milky Way, Andromeda is the largest nearby galaxy. Andromeda's population of bright young stars define its sweeping spiral arms in visible light images, but here the infrared view clearly follows the lumpy dust lanes heated by the young stars as they wind even closer to the galaxy's core. Constructed to explore Andromeda's infrared brightness and stellar populations, the full mosaic image is composed of about 3,000 individual frames. Two smaller companion galaxies, NGC 205 (below) and M32 (above) are also included in the combined fields. The data confirm that Andromeda (aka M31) houses around 1 trillion stars, compared to 4 hundred billion for the Milky Way.
說明:
史匹哲太空望遠鏡(Spitzer Space Telescope) 對距離兩百五十萬年光年遠的仙女座巨大璇渦狀星系，所拍攝的紅外線波段，很清楚的可以分辨出星塵(紅色)及星球(藍色)。 事實上，它的直徑將近本銀河系的兩倍，是我們附近最大的星系。 仙女座星系的懸臂，佈滿很亮的年輕星球，所以利用可見光波段的影像 可以輕易看到。但是從紅外線的影像則很清楚地見到，受到年輕星球的恆星風加熱，使得塵埃帶(dust lanes)呈現一個個的突起，而且非常接近星系核(galaxy's core)。 這張組合的照片是由 3,000 張照片所組成，用來探索仙女座星系的紅外線亮度及星球數目，兩個伴星系， NGC 205 (下方)及 M32 (上方)都包含在這張組合的照片中。 從資料上研讀仙女座星系約有一兆顆星，本銀河系則大約有四千億顆星。
資料來源: Scientific American
Department of Physics, NCKU
