Copyright:
Changsu Choi & Myungshin Im
(Seoul National University)
原文:
Sit back and watch a star explode. The actual supernova occurred back when dinosaurs roamed the Earth, but images of the spectacular event began arriving last year. Supernova 2015F was discovered in nearby spiral galaxy NGC 2442 by Berto Monard in 2015 March and was unusually bright — enough to be seen with only a small telescope. The pattern of brightness variation indicated a Type Ia supernova — a type of stellar explosion that results when an Earth-size white dwarf gains so much mass that its core crosses the threshold of nuclear fusion, possibly caused by a lower mass white-dwarf companion spiraling into it. Finding and tracking Type Ia supernovae are particularly important because their intrinsic brightness can be calibrated, making their apparent brightness a good measure of their distance — and hence useful toward calibrating the distance scale of the entire universe. The featured video tracked the stellar disruption from before explosion images arrived, as it brightened, and for several months as the fission-powered supernova glow faded. The remnants of SN2015F are now too dim to see without a large telescope. Just yesterday, however, the night sky lit up once again, this time with an even brighter supernova in an even closer galaxy: Centaurus A.
中文翻譯:
坐低，觀賞一顆星星的爆炸。這場超新星的實際爆炸發生在恐龍漫遊地球的時候，但壯觀事件的影像是在去年開始抵達的。超新星2015F是在2015年3月由Berto Monard在附近的螺旋星系NGC 2442中發現的，並且亮度異常高——足夠用小型望遠鏡便能見到。亮度變化的模式表明這是一顆Ia型超新星——一種當地球大小的白矮星獲得過多質量而其核心跨越核融合閾值時發生的恆星爆炸，可能是由一顆質量較低的白矮星伴星逐漸進入而引起的。尋找和追蹤Ia型超新星特別重要，因為它們的內在亮度可以進行校準，使它們的表觀亮度成為良好的距離測量，從而對校準整個宇宙的距離尺度非常有用。影片追蹤了這次恆星毀滅的過程，從爆炸前的影像開始，在亮度增加的期間，持續數月，直到裂變驅動的超新星光芒逐漸消退。超新星2015F的殘骸現在暗淡到不使用大型望遠鏡根本看不見。然而，就在昨天，夜空再次亮起，這次是一顆更亮的超新星，位於更近的星系：大犬座A。
#超新星 #觀察宇宙 #太空探索 #TypeIa超新星 #NGC2442 #科學探索 #黑暗中的光芒 #天文學 #星際現象 #超新星2015F #許多未知 #宇宙之美 #CentaurusA #星空奇觀
來源:NASA每日圖片
