Elliptical Galaxy Centaurus A from CFHT
影像版權與提供: Jean-Charles Cuillandre (CFHT), Hawaiian Starlight, CFHT
Explanation:
Why is peculiar galaxy Centaurus A so dusty? Dramatic dust lanes that run across the galaxy's center mark Cen A. These dust lanes are so thick they almost completely obscure the galaxy's center in visible light. This is particularly unusual as Cen A's red stars and round shape are characteristic of a giant elliptical galaxy, a galaxy type usually low in dark dust. Cen A, also known as NGC 5128, is also unusual compared to an average elliptical galaxy because it contains a higher proportion of young blue stars and is a very strong source of radio emission. Evidence indicates that Cen A is likely the result of the collision of two normal galaxies. During the collision, many young stars were formed, but details of the creation of Cen A's unusual dust belts are still being researched. Cen A lies only 13 million light years away, making it the closest active galaxy. Cen A, pictured above, spans 60,000 light years and can be seen with binoculars toward the constellation of Centaurus.
說明:
為什麼奇特的星系半人馬座A (Centaurus A; Cen A)會有這麼多塵埃？橫貫過半人馬座A中央的顯著塵埃帶，是這個星系的重要特點。這些塵埃帶是如此厚重，在可見光波段它們幾乎完全遮掩住星系的核心。這是一個非常不尋常的特徵，因為半人馬座A的紅色恆星和渾圓的外觀，在在顯示它是一個巨大的橢圓星系，而這種星系的塵埃含量通常很低。又名為NGC 5128的半人馬座A和尋常橢圓星系的其他差異有：較高比例的年輕藍色恆星和會發出很強的電波輻射，這些證據指向半人馬座A是二個正常星系互撞後的產物。星系的互撞觸發了眾多年輕恆星的誕生，不過半人馬座A不尋常的塵埃帶到底是怎麼產生的，仍待進一步研究與探索。人馬座A離我們只有1千3百萬光年遠，因此它是離我們最近的活躍星系。上面影像中的人馬座A，大小有六萬光年，可以用雙筒望遠鏡在南天的半人馬座內找到它。
資料來源: Scientific American
Department of Physics, NCKU
